SAFETY-24: an energy floor under the peak guard's forced discharge (#21)

SAFETY-07 could command a discharge to hold a billed quarter down and nothing below it consulted the state of charge - the BMS was the sole energy backstop. decide() now takes soc and soc_floor, and discharge_permitted() is the one place the question is answered: public, no default arguments, and consulted only AFTER a forced discharge is actually being asked for. The denied action is a 0 W floor - one-directional, forbids charging, structurally cannot cap the discharge the loop is already doing.

Reviewed independently. The trade-off is ruled honest and was made a check rather than a footnote: on a pack deliberately sized so the floor must bind, the worst quarter goes 4338 -> 5030 W while end SoC goes 9.6 -> 20.0 % and cycles pinned at the BMS cut-out go 1227 -> 0. Reproduced on the reviewer's own replay, including the 304.2 Wh withheld against 292.8 Wh between the two floors - half a cycle at the rail apart, so the floor is doing the arithmetic it claims.

The guard's central guarantee was re-derived across 19,800 combinations of load x elapsed x battery x SoC x floor: 0 negative floors, 0 claims with hi other than +inf, 0 decisions both floor-limited and saturated, 0 arbiter resolutions lowered or contradicted. Rule 8's <= is right: at equality the EMS floor could never be the thing that stops the discharge.

Eleven author mutations plus nine reviewer ones, all red under python -B with a purged __pycache__ and real byte deltas. One survivor is an equivalent mutant and provably so: a float(soc or 100) defaulting above the call site is dead code, because a Controller with no SoC never reaches decide() at all - inputs_ok is False and cycle() stops at the safety claim first. That property is now asserted on the service call, replacing an assertion whose sentence was wider than its check.

Merged after two rebases. The second one broke a grader neither card could have seen alone: test_peakguard graded the FIRST .decide( in main.py and required exactly one, which stopped being true when OPT-04 added arbitrage.decide(). It failed loudly rather than grading the wrong call. Fixed by selecting peakguard.decide by qualified name and requiring exactly one of that, verified still red on a decoy and on the maintenance_soc_floor swap.

Follow-ups filed as SAFETY-27, not addressed here: arbitrage_soc_floor has no rule-8 twin against bms_soc_floor, and this card's own 'revisit if a third floor appears' trigger has fired.

goodwe_controller/CHANGELOG.md

@@ -2,6 +2,50 @@
 
 ## Unreleased
 
+**The capacity-peak guard's forced discharge now has an EMS-side energy floor
+(SAFETY-24).** SAFETY-07 can command a discharge to hold a billed quarter down,
+and nothing below it consulted the state of charge — `soc_floor` belongs to the
+maintenance cycle, and freeze.py already recorded that for the grid-following
+loop "the BMS is the sole energy backstop". On the 2026-08-20 replay the guard
+asks for **878 Wh in a day**. Relying on the BMS is not absurd — it is a real
+floor and it works — but it is the pack's protection rather than the operator's,
+and a month of aggressive quarters leaves the battery repeatedly at that cut-out
+with no EMS-side record of why.
+
+`decide()` now takes `soc` and `soc_floor`, both **required** and neither
+defaulted. Above the floor nothing changes. At or below it the guard files a
+**0 W** floor instead of a sized one — one-directional, so charging stays blocked
+and no discharge is capped — and reports `floor_limited` with the reason it
+bound. It is not a trip: every stop in §11.2's table still outranks the claim,
+and the floor can never be negative, so §9.1's "discharge and export are never
+capped by the peak guard" survives as a property of the object (swept: 0 negative
+floors across 1296 combinations of load, elapsed, battery, SoC and floor).
+
+**Failing to shave is not silent.** A floor-limited cycle raises one notification
+per episode (`goodwe_peak_soc_floor`), distinct from the saturation alarm because
+the two ask the operator for opposite things, and renders its own status row.
+An **unreadable SoC is floor-limited, not a full battery** — a full battery is
+exactly the value that would disarm the floor, and this project has shipped that
+defaulting once before (`| float(100)` in the stage-5 loop).
+
+**Verified by replay, not by argument.** The 2026-08-20 capture is driven against
+a modelled pack sized from the day's own measured appetite, so it genuinely
+exhausts: without the floor it reaches the BMS cut-out and sits there for 1227
+guard cycles; with it the pack stops at 20.0 % and never touches the BMS. The
+energy withheld equals the energy between the two floors to within one cycle at
+the rail. The honest half is reported too — the worst quarter goes from 4338 W to
+5030 W, because a floor-limited guard shaves less on purpose.
+
+**Two new options, mirrored once.** `peak_soc_floor` (20) and `bms_soc_floor`
+(10), whose defaults live in `peakguard.PEAK_OPTION_DEFAULTS` — TARIFF-02's
+pattern — imported by `validate.py` and `main.py` rather than typed as literals,
+and pinned to `config.yaml` by a check that reads the file. CFG-03 still tracks
+three places. `validate.py` rule 8 refuses `peak_soc_floor <= bms_soc_floor` at
+startup, in CFG-01/MAINT-04's manner. `maintenance_soc_floor` is deliberately
+**not** reused and deliberately **not** renamed: it is a drain target, not a
+spend limit, and the rename is recorded as a decision to revisit if a third
+floor ever appears.
+
 **Price arbitrage - the first strategy that trades on a price (OPT-04).**
 Four cards built the price stack and nothing traded on it. `app/arbitrage.py`
 is §10.1's priority 3: charge in the cheapest published hour, discharge in the

goodwe_controller/DOCS.md

@@ -420,7 +420,7 @@ help - see "Why the tuning is what it is".
 | `maintenance_start_hour` | 10 | Hour of day a due cycle begins |
 | `maintenance_discharge_w` | 2000 | Drain rate (exports the surplus). Above `max_w` it is **clamped** to `max_w` — the drain phase SETs the setpoint and the arbiter bounds it, saying so on the status page (`limited by supervised(max_w)`). Warned about, not refused: the cycle still completes, just slower |
 | `maintenance_charge_w` | 2000 | Charge ceiling, capped again by peak headroom. Must stay **at or below `max_w`** or the cheap-window shaping (`hi = -maintenance_charge_w`) contradicts the supervised limit (`lo = -max_w`), the arbiter resolves it to **0 W**, and maintenance silently never charges in a cheap window — **the add-on refuses to start** |
-| `maintenance_soc_floor` | 11 | Drain target — stay just above the inverter's own floor |
+| `maintenance_soc_floor` | 11 | Drain target — stay just above the inverter's own floor. ⚠️ **This is not `peak_soc_floor`.** It is the depth the monthly recalibration deliberately goes to, once, on purpose; `peak_soc_floor` is the depth a money-saving discharge may never reach on any day. The right values differ (11 vs 20 as shipped), which is why they are two keys |
 | `maintenance_soc_target` | 99 | Charge target |
 | `maintenance_hold_min` | 120 | Hold at full so the BMS can balance |
 
@@ -430,6 +430,8 @@ help - see "Why the tuning is what it is".
 |---|---|
 | `peak_forecast_entity` | Quarter-hour demand forecast, for capacity-tariff markets. Empty = no cap |
 | `peak_cap_w` | The site's capacity-tariff target |
+| `peak_soc_floor` (20) | **The percent below which the capacity-peak guard will not discharge the battery.** Not optional and not the same thing as `maintenance_soc_floor` — see below |
+| `bms_soc_floor` (10) | The pack's **own** cut-out percent, the number the BMS enforces whatever you set above. `peak_soc_floor` must be **strictly above** it or the add-on refuses to start |
 | `price_now_entity`, `price_avg_entity` | Dynamic tariff. Empty = never force a paid grid top-up |
 
 On a capacity-tariff site the maintenance charge is capped by the headroom left
@@ -530,11 +532,46 @@ projected over — raises one notification (`goodwe_peak_saturated`), because th
 is the one state where the money will be spent and shedding load is the only
 thing left that changes the bill.
 
-**No new option.** The ceiling is `peak_cap_w`, which already shipped. The
+**No new option for the CEILING.** It is `peak_cap_w`, which already shipped. The
 coverage threshold is `meter_max_age_s`, the freeze predicate is
 `meter_freeze_s`, and the achievable discharge comes from `max_w` and the device
 rating — every one of them a key that already exists.
 
+#### The energy floor under the forced discharge (`peak_soc_floor`)
+
+The guard above can **command a discharge**, and until SAFETY-24 nothing in the
+add-on bounded how far down it took the pack — the BMS was the only backstop.
+On the 2026-08-20 replay the guard asks for **878 Wh in a day**.
+
+That is not absurd: the BMS floor is real and it works. But it is *the pack's*
+protection, not *yours*. A month of aggressive quarters can leave the battery
+repeatedly parked at that cut-out with no record on this side of why, and the
+first symptom — a battery that is never available when you want it — looks
+exactly like the SoC drift the monthly maintenance cycle exists to correct.
+
+- **`peak_soc_floor` (20 %)** is where the forced discharge stops. Below it the
+  guard files a **0 W** floor instead of a sized one: charging stays blocked
+  (that can only ever lower your offtake), and no further discharge is asked for.
+- **It does not stop the ordinary self-consumption loop.** That loop still has no
+  SoC guard of its own. This bounds what the *peak guard* spends for money.
+- **When it binds you are told**, once per episode, with notification
+  `goodwe_peak_soc_floor` and a status-page row reading `PEAK GUARD
+  FLOOR-LIMITED`: the quarter **will** go over the ceiling, so shedding load is
+  the only thing left that changes the bill. Failing to shave is never silent —
+  the euro figure is the whole point of the guard.
+- **An unreadable SoC is treated as floor-limited, not as a full battery.** A
+  full battery is exactly the value that would disarm this floor.
+- **`bms_soc_floor` (10 %)** is the pack's own cut-out — register `0x0560` on the
+  reference GW5000S-BP, consistent with DoD 90. It exists so the add-on can
+  **refuse to start** when `peak_soc_floor` is at or below it: such a floor can
+  never be the thing that stops the discharge, and a guard that advertises a
+  backstop it does not have is the one thing this project will not ship. Equal is
+  refused too — equal buys zero margin.
+
+Why 20 %: the reference pack is 13.8 kWh usable, so 10 points of margin over the
+BMS cut-out is about 1.6× the guard's worst measured day. If your pack is
+smaller, or your quarters are worse, raise it.
+
 ### The winding-loop alarm (the output clamp)
 
 Every setpoint this add-on writes is clamped to `max_w` before it leaves the

goodwe_controller/app/main.py

@@ -229,14 +229,25 @@ class Controller:
         # the action log and the notification fire on transitions rather than
         # once per cycle for a quarter of an hour.
         #
-        # ⚠️ NO CONFIG OF ITS OWN, for the reason the clamp watchdog gives ~90
+        # ⚠️ THE CEILING HAS NO CONFIG OF ITS OWN, for the reason the clamp
-        # lines up and TARIFF-01 repeats: the ceiling is `peak_cap_w`, already
+        # watchdog gives ~90 lines up and TARIFF-01 repeats: it is `peak_cap_w`,
-        # shipped and already validated, and every other term is read off
+        # already shipped and already validated, and every other term of the
-        # something the arbiter or the averager already owns. CFG-03 still
+        # projection is read off something the arbiter or the averager already
-        # tracks three places, not four.
+        # owns.
+        #
+        # ⚠️ SAFETY-24'S FLOOR DOES HAVE ONE, AND IT COULD NOT NOT HAVE. How far
+        # down the guard may spend the pack for money is a number only the site
+        # knows, and refusing one set below the pack's own cut-out means knowing
+        # that cut-out too. So this card adds exactly two keys and reads their
+        # defaults from `peakguard.PEAK_OPTION_DEFAULTS` - TARIFF-02's mirror
+        # pattern - rather than typing literals here. THAT is what keeps CFG-03
+        # at three places: the divergence validate.py's rule 6 documents
+        # (`maintenance_charge_w` 2000 there, 2500 here) is exactly what a
+        # literal in this file would repeat.
         self.peak_guard = None
         self._peak_engaged = False
         self._peak_saturated = False
+        self._peak_floor_limited = False
         self._maint_shape_suspended = False
         # Set by amain() once the transport is built, so the status page can show
         # what only the transport knows (homewizard_local's unchanged_s). Stays
@@ -534,6 +545,17 @@ class Controller:
             cap_w=float(self.o.get("peak_cap_w", 3500)),
             reading=self.peak.peak(now),
             achievable_w=min(max_w, abs(float(dev_top))),
+            # ⚠️ SAFETY-24. `self.soc` IS THE MEASURED READING AND MAY BE None,
+            # and it is handed over as None rather than defaulted here. An early
+            # draft of the stage-5 loop read SoC as `| float(100)` and thereby
+            # invented a full battery (NOTES.md 4.4b); a full battery is
+            # precisely the value that disarms this floor. decide() treats None
+            # as floor-limited, which is the direction that costs a shave rather
+            # than the pack.
+            soc=self.soc,
+            soc_floor=float(self.o.get(
+                "peak_soc_floor",
+                peakguard.PEAK_OPTION_DEFAULTS["peak_soc_floor"])),
             max_hold_s=self.p1.averager.max_hold_s,
             frozen=looks_frozen(getattr(self.p1_source, "unchanged_s", None),
                                 standing, max_w, self.freeze_wd.cfg),
@@ -780,6 +802,16 @@ class Controller:
         # method assigned above and nothing since has touched.
         await self.check_peak_saturated()
 
+        # --- SAFETY-24's alarm, and it is the OTHER way the money gets spent --
+        # Same boundary argument as check_peak_saturated(): it grades
+        # `self.peak_guard`, which cycle() assigned above and nothing since has
+        # touched. Kept as its own method rather than folded into that one,
+        # because the two states are mutually exclusive and want OPPOSITE
+        # operator actions - saturation says "shed load, the inverter is already
+        # flat out"; this says "the pack is at its floor and this quarter is not
+        # being shaved at all".
+        await self.check_peak_floor_limited()
+
         # --- TARIFF-01, and it is LAST on purpose -----------------------------
         # Banking a quarter is bookkeeping about a moment that has already
         # happened; a slow SD card must never sit between the meter and the
@@ -924,6 +956,70 @@ class Controller:
                 f"thing that changes the bill."),
         })
 
+    async def check_peak_floor_limited(self) -> None:
+        """SAFETY-24. Alarm when the EMS SoC floor stops the guard shaving.
+
+        ⚠️ FAILING TO SHAVE MUST NOT BE SILENT, AND THAT IS THE WHOLE POINT.
+        The guard exists for one euro figure - the capaciteitstarief bills the
+        month's single worst quarter - so a cycle in which it CHOSE not to shave
+        is a cycle in which money is being spent on purpose. Under-shaving
+        quietly would leave the operator with a bill and a status page full of
+        green.
+
+        The distinction from check_peak_saturated() is the operator's action,
+        which is why these are two notifications and not one:
+
+          saturated      the guard asked for everything the inverter has and it
+                         was not enough. SHED LOAD - the controller has already
+                         done all it can, and it is still discharging.
+          floor-limited  the guard asked for NOTHING, because the pack is at or
+                         under the EMS floor, or its SoC could not be read.
+                         Nothing is being discharged for this quarter at all.
+
+        They cannot both be true: peakguard.decide()'s floor-limited branch
+        returns before the `achievable_w` clamp that sets `saturated`.
+
+        Edge-triggered, and de-asserting arms it again - FreezeWatchdog's shape,
+        for FreezeWatchdog's reason: one notification per episode, not one per
+        cycle for a quarter of an hour.
+        """
+        g = self.peak_guard
+        limited = bool(g is not None and g.floor_limited)
+        was, self._peak_floor_limited = self._peak_floor_limited, limited
+        if not limited or was:
+            return
+        # No prefix: `reason` already opens with PEAK GUARD FLOOR-LIMITED, and
+        # a second copy is the kind of stutter that makes a 40-line action log
+        # read like boilerplate. The saturated path needs its prefix because its
+        # reason carries the word in the middle of a sentence, not at the front.
+        self.log_event(g.reason)
+        _LOG.error(
+            "SAFETY-24 - %s. The controller is STILL RUNNING and charging is "
+            "still blocked, but it is not discharging to hold this quarter, so "
+            "the quarter will set or raise the month's billed capacity peak. "
+            "Shed load, or lower peak_soc_floor if this pack can afford it.",
+            g.reason)
+        # A fixed notification_id, and a DIFFERENT one from every other alarm
+        # here - check_meter_frozen() gives the reasoning. A battery at its
+        # energy floor is not a saturated inverter and is not a frozen meter,
+        # and an operator who has to dismiss three identical-looking cards
+        # learns to dismiss the one that mattered.
+        await self.hass.call("persistent_notification", "create", {
+            "notification_id": "goodwe_peak_soc_floor",
+            "title": "GoodWe: the capacity-peak guard has run out of battery",
+            "message": (
+                f"{g.reason}.\n\nTHIS QUARTER WILL GO OVER THE "
+                f"{g.ceiling_w:.0f} W ceiling and will set or raise the "
+                f"month's billed capaciteitstarief peak, because the peak guard "
+                f"is not allowed to discharge any further: {g.soc_floor_reason}."
+                f" This is not a controller fault - it is the EMS-side energy "
+                f"floor (peak_soc_floor) doing what it is set to do, and it sits "
+                f"deliberately above the pack's own BMS cut-out. Charging stays "
+                f"blocked. Shedding load is the only thing that changes the bill "
+                f"now; if this pack can afford a deeper discharge, lower "
+                f"peak_soc_floor."),
+        })
+
     async def check_meter_frozen(self) -> None:
         """SAFETY-18. Alarm on a meter that answers forever without changing.
 
@@ -1265,6 +1361,13 @@ class Controller:
             elif _pg.saturated:
                 out.append({"ok": False, "warn": False,
                             "text": "PEAK GUARD SATURATED - " + _pg.reason})
+            elif _pg.floor_limited:
+                # SAFETY-24. NOT ok, like saturation: in both states the money
+                # is going to be spent and a human is the only actuator left. A
+                # separate row from saturation because the two ask for opposite
+                # things - see check_peak_floor_limited().
+                out.append({"ok": False, "warn": False,
+                            "text": _pg.explain()})
             elif _pg.blind:
                 out.append({"ok": False, "warn": True, "text": _pg.explain()})
             else:

goodwe_controller/app/peakguard.py

@@ -246,19 +246,100 @@ validate.py are untouched by this ticket, exactly as TARIFF-01 left them, and
 mismatch trap 14's own warning box describes.
 
 ------------------------------------------------------------------------------
-⚠️ WHAT THIS GUARD DOES NOT HAVE: AN ENERGY BACKSTOP. SEE SAFETY-24.
+SAFETY-24: THE ENERGY BACKSTOP THIS GUARD SHIPPED WITHOUT
 
-The graded branch can FORCE DISCHARGE, and nothing in this file or in the loop
+SAFETY-07 left this file saying, in its own words, that the graded branch can
-below it consults the state of charge - `soc_floor` belongs to the maintenance
+FORCE DISCHARGE and that nothing below it consults the state of charge - "the
-cycle, and freeze.py already records that for the grid-following loop "the BMS
+BMS is the sole energy backstop" (freeze.py). On the 2026-08-20 replay the guard
-is the sole energy backstop". On the 2026-08-20 replay the guard asks for 878 Wh
+asks for 878 Wh in a day, and it keeps asking for as long as the meter says the
-in a day. Against a pack sitting near 9 % that is not nothing, and the guard will
+quarter is over the ceiling. That is the behaviour working as designed, and it
-keep asking as long as the meter says the quarter is over the ceiling.
+is unbounded from below by anything in the EMS.
 
-That is deliberate for THIS card and it is filed as SAFETY-24. It is also the
+⚠️ STATE THE RISK FAIRLY, because overstating it is how a real one gets ignored.
-reason this must not go to a client install before SAFETY-24 lands: on the
+Relying on the BMS is not absurd: it is a genuine floor and it works. But it is
-reference site the BMS is a known quantity and an operator is present, and on a
+THE PACK's protection, not the OPERATOR's. A month of aggressive quarters can
-client site neither is true.
+leave the battery repeatedly parked at that floor with no EMS-side record of
+why, and the first symptom - a pack that is never available when it is wanted -
+is indistinguishable from the SoC drift MAINT-01 exists to correct.
+
+So `decide()` now takes `soc` and `soc_floor`, and `discharge_permitted()` is
+the one place the question is answered. Four things about the shape of it:
+
+  1. IT IS NOT A TRIP, AND IT MUST NOT BECOME ONE. SAFETY-07's claim is a LIMIT
+     and every stop in 11.2's table still outranks it. This floor is about
+     ENERGY - how far down the guard may spend the pack for money - not about
+     last-resort safety. The action when it binds is therefore to stop ASKING
+     for more discharge, not to command anything.
+
+  2. THE ACTION IS `floor_w = 0.0`, WHICH IS THE BLIND BRANCH'S ACTION FOR THE
+     BLIND BRANCH'S REASON. Zero is one-directional: it forbids CHARGING, which
+     can only ever lower delivered offtake, and it forbids nothing else. It
+     cannot pull the loop off a discharge it is already doing, because a `lo`
+     limit structurally cannot cap discharge - the property this module's whole
+     shape rests on, and one a NEGATIVE floor would destroy. Nothing here can
+     produce a negative floor: the only two values `floor_w` ever takes are 0.0
+     and `min(wanted, achievable)` with `wanted > 0` already established.
+
+     ⚠️ AND IT DOES NOT BOUND THE LOOP. Self-consumption may still drain the
+     pack past this floor, exactly as SAFETY-18 recorded. That is not fixed
+     here and must not be claimed: this card bounds THE PEAK GUARD's OWN forced
+     discharge, which is the thing SAFETY-07 introduced. A loop-side SoC guard
+     is a different lever with a different right value.
+
+  3. IT IS GRADED ONLY WHERE IT IS NOT DEGENERATE. The SoC question is asked
+     AFTER `wanted > 0` is established - i.e. only where a forced discharge is
+     actually being asked for. Asked earlier it would grade a quantity that
+     governs nothing, and would report "floor-limited" on a quiet afternoon
+     where the guard was never going to discharge anyway.
+
+  4. AN UNREADABLE SoC IS NOT A FULL BATTERY. `soc=None` is floor-limited, not
+     permitted. This is `PeakReading`'s lesson in the one place it bites
+     hardest: a full battery is exactly the value that would disarm this floor,
+     so a failed read defaulting to one would silently restore the unbounded
+     discharge this card exists to remove. Both new arguments are REQUIRED
+     keyword-only and neither has a default, which is TEST-14 read as a rule
+     rather than as a story: a required field that gains a default is how three
+     separate files in this repo shipped a quiet fallback.
+
+AND FAILING TO SHAVE MUST NOT BE SILENT. The whole point of the guard is the
+euro figure, so a floor-limited cycle carries `floor_limited=True` and main.py
+raises ONE notification on the edge, saying the quarter will be exceeded - the
+same shape, and the same argument, as `saturated`. The two are mutually
+exclusive by construction: a floor-limited decision asks for nothing, so it
+cannot have run out of inverter.
+
+------------------------------------------------------------------------------
+CFG-03: TWO NEW OPTIONS, MIRRORED ONCE, AND WHY BOTH ARE NEEDED
+
+SAFETY-07 added none and said so. This card cannot: an EMS-side floor is a
+number only the site knows, and refusing one set below the pack's own cut-out
+means knowing that cut-out too.
+
+  * `peak_soc_floor` - the EMS floor. ⚠️ NOT `maintenance_soc_floor`. That is
+    the maintenance cycle's DRAIN TARGET: the depth a monthly recalibration
+    deliberately goes to, once, under supervision. This is the depth a
+    money-saving discharge may never reach, on any day of the month. Sharing
+    one key would couple two features whose right values differ and would widen
+    CFG-03 rather than narrow it.
+  * `bms_soc_floor` - the pack's own cut-out (register 0x0560 on the reference
+    unit, 10 %). It is here so validate.py rule 8 can REFUSE a `peak_soc_floor`
+    at or below it. That configuration is CFG-01 rule (a): the operator states
+    a floor, the BMS enforces a different one, and the status page reports an
+    energy backstop that can never bind.
+
+Both defaults are mirrored ONCE, in `PEAK_OPTION_DEFAULTS` below, which is
+TARIFF-02's `PRICE_OPTION_DEFAULTS` pattern - imported by validate.py and by
+main.py, pinned to config.yaml by test_peakguard.py rather than transcribed.
+This module still reads no option itself: `decide()` takes both as ARGUMENTS,
+makes no `.get()` call, and the mirror is a default table, not a read.
+
+⚠️ A DECISION RECORDED, NOT A RENAME DONE. Now that a second SoC floor exists,
+`maintenance_soc_floor` is the ambiguous name of the two - it reads like "the
+SoC floor" and is not. Renaming it is an option migration on a live install for
+a clarity gain, so the decision recorded here is: KEEP IT, and carry the
+distinction in DOCS.md and in this comment. Revisit if a THIRD floor appears -
+a loop-side guard would be the third - at which point the migration buys enough
+to be worth its cost.
 
 ------------------------------------------------------------------------------
 AND IT READS NO PER-PHASE QUANTITY, ON PURPOSE
@@ -287,8 +368,44 @@ BLIND_FROZEN = "SAFETY-18: the meter is answering without changing"
 CEILING_CAP = "peak_cap_w"
 CEILING_MONTH_PEAK = "the month's banked peak"
 
+# SAFETY-24. Why the forced discharge may not be sized. Reasons, not booleans,
+# for BLIND_*'s reason: the status page, the action log and the operator
+# notification all have to say WHICH, and "floor-limited" alone is unactionable.
+FLOOR_SOC_UNREADABLE = ("the battery state of charge was not measured this "
+                        "cycle, and an unreadable SoC is not a full battery")
+FLOOR_AT_SOC_FLOOR = "state of charge is at or below the peak guard's SoC floor"
+
 SOURCE = "peak"
 
+# ⚠️ CFG-03. THE ONE IN-CODE MIRROR OF config.yaml FOR THIS CARD'S OPTIONS, and
+# it is TARIFF-02's `PRICE_OPTION_DEFAULTS` pattern for TARIFF-02's reason: the
+# add-on already carries option defaults in three places (config.yaml's
+# `options:`, config.yaml's `schema:`, and main.py's literal `.get()`
+# fallbacks), and a fourth is the open ticket. validate.py and main.py both
+# import THIS dict rather than typing a literal, and test_peakguard.py pins it
+# to config.yaml by READING the file - so a drift goes red instead of shipping.
+#
+# ⚠️ NOT A READ. `decide()` takes both values as arguments and this module makes
+# no `.get()` call at all; the dict is a default table for its two callers.
+PEAK_OPTION_DEFAULTS = {
+    # The EMS-side floor on SAFETY-07's forced discharge, in percent.
+    #
+    # 20 is DERIVED from the two numbers this repository already has, not
+    # chosen. The reference pack is 300 Ah at 51.2 V with DoD 90 - 13.8 kWh
+    # usable, the figure validate.py's rule 6 note already quotes - and the
+    # 2026-08-20 replay models 878 Wh of guard discharge in a day, which is
+    # 6.4 % of that. A floor 10 points above the pack's own 10 % cut-out
+    # therefore leaves the guard roughly 1.6 of its worst observed days of room
+    # before it stops, which is the smallest margin that lets the guard do its
+    # job on a bad day and still never reach the BMS.
+    "peak_soc_floor": 20,
+    # The pack's OWN cut-out, in percent: what the BMS enforces regardless of
+    # anything here. On the reference unit this is register 0x0560, read as 10,
+    # and it is consistent with DoD 90 on a full pack. It exists so validate.py
+    # rule 8 can refuse a `peak_soc_floor` at or below it - see that rule.
+    "bms_soc_floor": 10,
+}
+
 
 @dataclass(frozen=True)
 class PeakDecision:
@@ -309,9 +426,19 @@ class PeakDecision:
     excess_w: float = 0.0
     wanted_w: float | None = None    # the floor before `achievable_w` clamped it
     saturated: bool = False
+    # SAFETY-24. True when a forced discharge WAS wanted and the EMS-side SoC
+    # floor refused to size it. Mutually exclusive with `saturated` by
+    # construction: this branch asks for nothing, so it cannot have run out of
+    # inverter. `soc_floor_reason` says WHICH of the two ways it bound.
+    floor_limited: bool = False
+    soc: float | None = None
+    soc_floor: float | None = None
+    soc_floor_reason: str | None = None
     reason: str = ""
 
     def explain(self) -> str:
+        if self.floor_limited:
+            return self.reason
         if not self.engaged:
             if self.projected_w is None:
                 return f"peak guard idle - {self.reason}"
@@ -383,7 +510,44 @@ def blindness(projection, max_hold_s, frozen: bool) -> str | None:
     return None
 
 
-def decide(projection, *, batt_w, cap_w, reading, achievable_w,
+def discharge_permitted(soc, soc_floor) -> str | None:
+    """SAFETY-24. May the guard size a forced discharge, or why may it not?
+
+    Returns None when it may, and otherwise the REASON it may not - which the
+    decision, the status page, the action log and the operator notification all
+    carry, because "floor-limited" on its own tells nobody what to do.
+
+    THE ONE PLACE THIS QUESTION IS ANSWERED, and it is public for the reason
+    `freeze.looks_frozen()`, `watchdog.loop_is_following()` and
+    `shaping_suspended()` are: a safety predicate transcribed into its own check
+    is one copy plus a future disagreement about what the check means, and the
+    copy that drifts is always the grading one.
+
+    ⚠️ `soc is None` IS NOT PERMISSION. A failed read is not an observation, and
+    a FULL BATTERY is exactly the value that would disarm this floor - so a
+    `float(soc or 100)` here would restore the unbounded discharge this card
+    removes, silently, on the one install whose SoC sensor is misnamed. There is
+    deliberately no default argument on either parameter.
+
+    ⚠️ AND `soc_floor is None` IS NOT PERMISSION EITHER, for the same reason one
+    step further out: a caller that has no floor configured has not thereby been
+    granted an unbounded one.
+
+    Boundary: `<=`, not `<`. A pack sitting exactly ON the floor has already
+    spent everything this guard was allowed to spend; permitting one more cycle
+    there would make the floor mean "one cycle below the floor".
+    """
+    if soc is None:
+        return FLOOR_SOC_UNREADABLE
+    if soc_floor is None:
+        return ("no peak guard SoC floor is configured, so there is nothing to "
+                "bound a forced discharge with")
+    if float(soc) <= float(soc_floor):
+        return FLOOR_AT_SOC_FLOOR
+    return None
+
+
+def decide(projection, *, batt_w, cap_w, reading, achievable_w, soc, soc_floor,
            max_hold_s=None, frozen: bool = False) -> PeakDecision:
     """The whole guard. Pure: no clock, no I/O, no state carried between calls.
 
@@ -395,6 +559,13 @@ def decide(projection, *, batt_w, cap_w, reading, achievable_w,
                    claim can NEVER produce `lo > hi` in the resolver - a
                    contradiction there resolves to 0 W, which would park the
                    battery in the exact minute it should be discharging hardest.
+    `soc`          SAFETY-24. MEASURED state of charge, percent. None when the
+                   sensor for it did not answer - which is floor-limited, not
+                   permission.
+    `soc_floor`    SAFETY-24. The percent below which this guard may not spend
+                   the pack for money. REQUIRED, and deliberately without a
+                   default: a default here would be CFG-03's fourth defaults
+                   site and TEST-14's quiet fallback in one line.
     """
     ceiling, from_where = quarter_ceiling_w(cap_w, reading)
     ceil_top = abs(float(achievable_w))
@@ -454,12 +625,41 @@ def decide(projection, *, batt_w, cap_w, reading, achievable_w,
             wanted_w=wanted,
             reason="the load is under the level this quarter can afford")
 
+    # SAFETY-24 - AND ONLY HERE. `wanted > 0` is now established, so a forced
+    # discharge really is being asked for and the SoC is the quantity that
+    # decides whether it may be sized. Asked one line earlier it would grade a
+    # number that governs nothing on every quiet cycle of the day, and would
+    # report "floor-limited" over a guard that was never going to discharge.
+    denied = discharge_permitted(soc, soc_floor)
+    if denied is not None:
+        # 0.0, not `wanted`, and not a negative number. Zero forbids CHARGING -
+        # one-directional, cannot cost pack energy - and forbids nothing else;
+        # a `lo` limit structurally cannot cap the discharge the loop is already
+        # doing. See the module note: this bounds THE GUARD's forced discharge,
+        # not the grid-following loop, which still has no SoC guard.
+        return PeakDecision(
+            engaged=True, floor_w=0.0, ceiling_w=ceiling,
+            ceiling_from=from_where, projected_w=projected, excess_w=ex,
+            wanted_w=wanted, floor_limited=True, soc=soc, soc_floor=soc_floor,
+            soc_floor_reason=denied,
+            reason=(
+                f"PEAK GUARD FLOOR-LIMITED: the quarter projects "
+                f"{projected:.0f} W against a {ceiling:.0f} W ceiling "
+                f"({from_where}) and {wanted:+.0f} W of discharge would hold "
+                f"it, but {denied}"
+                + ("" if soc is None else f" ({float(soc):.0f} %")
+                + ("" if soc is None or soc_floor is None
+                   else f" vs {float(soc_floor):.0f} %")
+                + ("" if soc is None else ")")
+                + " - commanding no forced discharge, so THIS QUARTER WILL GO "
+                  "OVER THE CEILING. Charging stays blocked (floor 0 W)"))
+
     floor = min(wanted, ceil_top)
     saturated = floor < wanted
     return PeakDecision(
         engaged=True, floor_w=floor, ceiling_w=ceiling, ceiling_from=from_where,
         blind=None, projected_w=projected, excess_w=ex, wanted_w=wanted,
-        saturated=saturated,
+        saturated=saturated, soc=soc, soc_floor=soc_floor,
         reason=(
             f"PEAK GUARD: quarter projects {projected:.0f} W against a "
             f"{ceiling:.0f} W ceiling ({from_where}) with "
@@ -513,5 +713,13 @@ def claim(decision: PeakDecision) -> Claim | None:
     """
     if not decision.engaged or decision.floor_w is None:
         return None
+    # Three reasons, not two. A `lo = 0 W` claim reaches the arbiter from THREE
+    # different states now - blind, floor-limited, and a genuine floor that
+    # happens to be zero - and the arbiter's explain() is what an operator reads
+    # when the battery stops charging. Spelling them the same way would make the
+    # SAFETY-24 case indistinguishable from the SAFETY-18 one on the one line
+    # that gets read.
     return Claim.limit(SOURCE, P_PEAK, lo=float(decision.floor_w),
-                       reason=("blind" if decision.blind else "quarter peak"))
+                       reason=("blind" if decision.blind
+                               else "SoC floor" if decision.floor_limited
+                               else "quarter peak"))

goodwe_controller/app/validate.py

@@ -131,6 +131,25 @@ NOT READY banner already names the problem, (b) does not apply.
      installed base is on a fixed or static tariff. Refusing to start without a
      price feed would lock those sites out of the add-on entirely.
 
+  8. `peak_soc_floor` at or below `bms_soc_floor`.  [(a)]
+     SAFETY-24, and the same shape as 1, 4, 5 and 6. The peak guard can COMMAND
+     a discharge to hold a billed quarter down (SAFETY-07), and `peak_soc_floor`
+     is the EMS-side bound on how far down it may take the pack. The BMS has its
+     own cut-out and enforces it regardless. Set the EMS floor at or below that
+     cut-out and THE BMS WINS: the EMS bound can never be the thing that stops
+     the discharge, so the add-on carries an energy backstop that is incapable
+     of binding while its status page reports one - rule 5's "a disarmed guard
+     that advertises itself as armed", on the guard whose failure mode is a pack
+     that is quietly never available when it is wanted.
+
+     ⚠️ `<=`, NOT `<`, and the equality case is the interesting one. At exactly
+     equal, the EMS floor and the pack's cut-out act at the same percent, so the
+     EMS floor buys ZERO margin - it can never prevent the pack reaching the BMS
+     limit, which is the entire thing this option exists to prevent. That is not
+     "close to the rail", it is the disarmed case with an extra step. Rule 6
+     permits equality because equality there leaves one reachable point that
+     works; here it leaves none.
+
 WHAT IS DELIBERATELY *NOT* REFUSED, because it is untidy rather than unsafe:
 
   - `integrator_max_w` above `max_w`. DOCS.md is right that the only thing the
@@ -151,12 +170,17 @@ WHAT IS DELIBERATELY *NOT* REFUSED, because it is untidy rather than unsafe:
   - `maintenance_discharge_w` above `max_w`. Clamped, not contradicted, and the
     clamp names itself in the arbiter's explain() - see rule 6. Warned about,
     not refused.
+  - `peak_soc_floor` below `maintenance_soc_floor`, or above it. They are
+    DIFFERENT QUANTITIES (SAFETY-24: a drain target versus a spend limit) and
+    every ordering of the two is a legitimate site configuration. Refusing on
+    an ordering would be inventing a relationship the system does not have.
 """
 
 import logging
 
 from .arbitrage import enabled as arbitrage_on
 from .p1 import is_enabled, validate_meter_options
+from .peakguard import PEAK_OPTION_DEFAULTS
 from .price import PRICE_OPTION_DEFAULTS, PROVIDERS
 from .static_tariff import ProfileInvalid, parse_static_profile
 
@@ -370,6 +394,36 @@ def validate_startup_config(opts: dict, dev_min=None, dev_max=None) -> list[str]
     # --- 7. two price sources on one site ------------------------------------
     problems.extend(_price_problems(opts))
 
+    # --- 8. an EMS energy floor the BMS does not already enforce -------------
+    # ⚠️ THE FALLBACKS ARE peakguard.PEAK_OPTION_DEFAULTS, NOT LITERALS, and
+    # that is CFG-03 read as a rule rather than as a complaint. Rule 6's own
+    # comment documents a LIVE divergence in this repo caused by typing 2000
+    # here and 2500 in main.py; this card refuses to add a second instance of
+    # it. The dict is the single in-code mirror, pinned to config.yaml by
+    # test_peakguard.py, and main.py reads the same one.
+    soc_floor = _number(opts, "peak_soc_floor",
+                        PEAK_OPTION_DEFAULTS["peak_soc_floor"])
+    bms_floor = _number(opts, "bms_soc_floor",
+                        PEAK_OPTION_DEFAULTS["bms_soc_floor"])
+    if soc_floor is None or bms_floor is None:
+        problems.append(
+            "peak_soc_floor and bms_soc_floor must both be numbers (got "
+            f"{opts.get('peak_soc_floor')!r} / {opts.get('bms_soc_floor')!r})")
+    elif soc_floor <= bms_floor:
+        problems.append(
+            f"peak_soc_floor is {soc_floor:.0f} % but the pack's own cut-out "
+            f"(bms_soc_floor) is {bms_floor:.0f} %, so SAFETY-07's forced "
+            "discharge has no EMS-side bound at all - THE BMS WINS, and it is "
+            "the pack's protection rather than yours. The guard would report a "
+            "SoC floor on its status page while being incapable of ever being "
+            "the thing that stops the discharge, and the symptom of that is a "
+            "battery repeatedly sitting at the BMS limit with no record of why "
+            f"- which looks exactly like the SoC drift the maintenance cycle "
+            f"exists to correct. Raise peak_soc_floor above {bms_floor:.0f} % "
+            f"(the shipped default is "
+            f"{PEAK_OPTION_DEFAULTS['peak_soc_floor']:.0f} %), or correct "
+            "bms_soc_floor if it does not match this pack.")
+
     # --- warnings: real, but not worth refusing over -------------------------
     integ = opts.get("integrator_max_w")
     integ_w = None if not integ else _number(opts, "integrator_max_w", None)

goodwe_controller/config.yaml

@@ -163,6 +163,37 @@ options:
   peak_forecast_entity: ""
   peak_cap_w: 3500
 
+  # --- SAFETY-24: the energy backstop under SAFETY-07's forced discharge -----
+  # The peak guard can COMMAND a discharge to hold a billed quarter under
+  # peak_cap_w. Until this card it was bounded from below by nothing but the
+  # pack's own BMS cut-out - a real floor, but the PACK's protection rather than
+  # the OPERATOR's. On the 2026-08-20 replay the guard asks for 878 Wh in a day.
+  #
+  # peak_soc_floor is the percent below which that discharge is not sized. When
+  # it binds the guard reports FLOOR-LIMITED, keeps charging blocked (a 0 W
+  # floor), and the add-on raises ONE notification saying the quarter will be
+  # exceeded - failing to shave is never silent, because the euro figure is the
+  # whole point of the guard.
+  #
+  # ⚠️ THIS IS NOT maintenance_soc_floor AND MUST NOT BE MERGED WITH IT.
+  # maintenance_soc_floor is the DRAIN TARGET of the monthly recalibration: the
+  # depth the cycle deliberately goes to, once a month, on purpose. This is the
+  # depth a money-saving discharge may never reach on any day. The right values
+  # differ, and sharing one key would couple two features that want to move
+  # independently.
+  #
+  # ⚠️ 20 IS DERIVED, NOT PICKED. The reference pack is 13.8 kWh usable and the
+  # worst modelled guard day is 878 Wh, i.e. 6.4 % - so 10 points above the
+  # pack's own cut-out leaves the guard ~1.6 of its worst observed days of room
+  # and still never reaches the BMS.
+  peak_soc_floor: 20
+  # The pack's OWN cut-out percent - what the BMS enforces whatever is set
+  # above. Register 0x0560 reads 10 on the reference GW5000S-BP, consistent with
+  # DoD 90. It is here so validate.py can REFUSE a peak_soc_floor at or below
+  # it: such a floor can never bind, the BMS wins, and the status page would
+  # report an energy backstop that does not exist.
+  bms_soc_floor: 10
+
   # ⚠️ THE OLD PRICE PATH, AND IT IS NOT DEAD YET. These two entities are the
   # add-on delegating the whole price question to Home Assistant: main.py reads
   # both and derives ONE BOOLEAN, `cheap = now <= avg`, which is consumed by
@@ -343,6 +374,12 @@ schema:
 
   peak_forecast_entity: str?
   peak_cap_w: int(500,15000)
+  # SAFETY-24. No "off" value: a guard that can command a discharge does not get
+  # a supported way to have no energy bound at all. The ranges OVERLAP on
+  # purpose - the schema cannot express "above bms_soc_floor", so validate.py
+  # rule 8 is what refuses the pair, with a message naming both numbers.
+  peak_soc_floor: int(5,60)
+  bms_soc_floor: int(0,50)
   price_now_entity: str?
   price_avg_entity: str?
 

goodwe_controller/test_peakguard.py

@@ -2,7 +2,7 @@
 
     python3 test_peakguard.py
 
-Eight parts. What each is for, and - where it matters - what it is deliberately
+Ten parts. What each is for, and - where it matters - what it is deliberately
 NOT allowed to be tested at:
 
   1. THE CONTROL LAW, `excess_w`, graded AWAY from the two points where it is
@@ -36,8 +36,18 @@ NOT allowed to be tested at:
   6. THE REPLAY. 2026-08-20's 5029.8 W billed quarter, closed-loop, and the
      healthy day's baseline. Every figure re-derived from the committed capture.
   7. THE WIRING, through the real `Controller.cycle()` and its real status page.
-  8. MUTATION. Six one-line defeats of this guard, each run against the checks
+  8. SAFETY-24: THE ENERGY FLOOR under the forced discharge, graded only where
-     above to show they are not vacuous.
+     a forced discharge is actually being asked for - the SoC is a degenerate
+     stimulus on every cycle where `wanted <= 0`, and grading it there is how
+     six bugs hid in this repository this week. Includes the sweep that shows
+     the floor is never negative, which is the property the whole `lo`-limit
+     shape rests on.
+  9. THE EXHAUSTING REPLAY (AC 4) AND THE STARTUP REFUSAL. The same 2026-08-20
+     capture, against a MODELLED PACK small enough that the guard's own 878 Wh
+     day would take it to the BMS cut-out - so the two worlds, before and after
+     this card, are run against each other rather than reasoned about.
+ 10. MUTATION. Eleven one-line defeats of these two guards, each run against
+     the checks above to show they are not vacuous.
 
 ------------------------------------------------------------------------------
 WHAT THE REPLAY IS AND IS NOT
@@ -66,7 +76,9 @@ support: the same quarters, with and without the guard.
 
 import asyncio
 import ast
+import dataclasses
 import gzip
+import inspect
 import json
 import re
 import shutil
@@ -89,9 +101,11 @@ from app.p1 import (
 )
 from app.peakguard import (
     BLIND_COVERAGE, BLIND_FROZEN, BLIND_NO_BLOCK, CEILING_CAP,
-    CEILING_MONTH_PEAK, PeakDecision, blindness, decide, excess_w,
+    CEILING_MONTH_PEAK, FLOOR_AT_SOC_FLOOR, FLOOR_SOC_UNREADABLE,
-    quarter_ceiling_w, uncovered_s,
+    PEAK_OPTION_DEFAULTS, PeakDecision, blindness, decide, discharge_permitted,
+    excess_w, quarter_ceiling_w, uncovered_s,
 )
+from app.validate import validate_startup_config
 from app.tariff import (
     NOT_OBSERVED, NO_RECORD, OBSERVED, PeakReading, PeakStore, PeakTracker,
     month_key,
@@ -166,13 +180,29 @@ CYCLE_S = read_option("cycle_floor_s")
 # ceiling and the GW5000S-BP's rating, which is why the two agree - so the
 # device figure is taken from the schema rather than typed.
 LIVE_MAX_W = read_schema_max("max_w")
+# SAFETY-24's two options, out of the shipped file for the same reason.
+SOC_FLOOR = read_option("peak_soc_floor")
+BMS_FLOOR = read_option("bms_soc_floor")
+MAINT_FLOOR = read_option("maintenance_soc_floor")
+# A state of charge that comfortably permits a forced discharge, DERIVED from
+# the floor rather than typed: every part of this file that is not about
+# SAFETY-24 has to grade SAFETY-07's behaviour at a SoC where the new floor is
+# not the thing deciding the answer, or it would be measuring the wrong guard.
+SOC_OK = SOC_FLOOR + 30.0
 
 print("SAFETY-07 - the quarter-peak projection guard")
+print("SAFETY-24 - and the energy floor under its forced discharge")
 print(f"    read from config.yaml: peak_cap_w {CAP_W:.0f} W, "
       f"meter_max_age_s {MAX_HOLD_S:.0f} s, meter_freeze_s {FREEZE_S:.0f} s, "
       f"cycle_floor_s {CYCLE_S:.0f} s, max_w schema ceiling {LIVE_MAX_W:.0f} W")
+print(f"    ...and peak_soc_floor {SOC_FLOOR:.0f} %, bms_soc_floor "
+      f"{BMS_FLOOR:.0f} %, maintenance_soc_floor {MAINT_FLOOR:.0f} %")
 check("every threshold this check grades against came out of config.yaml",
-      None not in (CAP_W, MAX_HOLD_S, FREEZE_S, CYCLE_S, LIVE_MAX_W))
+      None not in (CAP_W, MAX_HOLD_S, FREEZE_S, CYCLE_S, LIVE_MAX_W,
+                   SOC_FLOOR, BMS_FLOOR, MAINT_FLOOR))
+check("...and the SoC these checks use as 'plenty of battery' is comfortably "
+      "clear of the floor, so nothing outside part 9 is silently grading "
+      "SAFETY-24 instead of SAFETY-07", SOC_OK > SOC_FLOOR + 10.0)
 
 B = datetime(2026, 8, 30, 9, 0, 0, tzinfo=timezone.utc)   # a quarter boundary
 
@@ -239,7 +269,7 @@ BATT_NOW = 400.0
 a_edge = averager_at(CEIL, 450.0)
 p_edge = PeakTracker.project(a_edge, B + timedelta(seconds=450))
 d_edge = decide(p_edge, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
-                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 e_edge = excess_w(p_edge, CEIL)
 print(f"    held exactly AT the ceiling for 450 s: projected "
       f"{p_edge.projected_w:.2f} W, excess {e_edge:.3f} W, "
@@ -254,7 +284,7 @@ check("at the engagement boundary the excess is zero, so the floor is exactly "
 # released as soon as `excess <= 0` hands the actuator back at the exact instant
 # it is working, and the load springs straight back.
 released = decide(p_edge, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
-                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 would_release_on_excess = excess_w(p_edge, CEIL) <= 0.0
 print(f"    at the boundary: excess {e_edge:.3f} W (an `excess > 0` test would "
       f"RELEASE: {would_release_on_excess}), floor {released.floor_w:.0f} W "
@@ -266,7 +296,7 @@ check("...and the claim is held there, not released. `excess` falls to zero as "
 d_gone = decide(PeakTracker.project(averager_at(500.0, 450.0),
                                     B + timedelta(seconds=450)),
                 batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
-                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 check("...and it DOES release once the load falls under what the quarter can "
       "afford, so 'threshold the floor' is not 'never let go'",
       not d_gone.engaged and d_gone.floor_w is None)
@@ -275,7 +305,7 @@ check("...and it DOES release once the load falls under what the quarter can "
 a_over = averager_at(CEIL + 200.0, 450.0)
 p_over = PeakTracker.project(a_over, B + timedelta(seconds=450))
 d_over = decide(p_over, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
-                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 print(f"    200 W over for 450 s: {d_over.explain()}")
 check("a quarter projected over the ceiling engages, and the floor is the "
       "MEASURED battery power plus the derived excess",
@@ -284,7 +314,7 @@ check("a quarter projected over the ceiling engages, and the floor is the "
 check("...and the floor moves with the battery measurement, so it is a claim "
       "about delivered power rather than a fixed setpoint",
       not near(decide(p_over, batt_w=BATT_NOW + 250.0, cap_w=CAP_W, reading=None,
-                      achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S).floor_w,
+                      achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR).floor_w,
                d_over.floor_w, 1.0))
 
 # THE WIND-UP ARGUMENT, made concrete. A floor built on INTENT re-adds its own
@@ -295,7 +325,7 @@ delivered_floor = []
 intent_floor = []
 for _ in range(5):
     d_del = decide(p_over, batt_w=stuck_batt, cap_w=CAP_W, reading=None,
-                   achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                   achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
     delivered_floor.append(d_del.floor_w)
     intent = intent + excess_w(p_over, CEIL)     # what the intent form would do
     intent_floor.append(intent)
@@ -378,7 +408,7 @@ absurd = averager_at(LIVE_MAX_W * 4, 870.0)
 p_absurd = PeakTracker.project(absurd, B + timedelta(seconds=870))
 DEV_MAX = LIVE_MAX_W - 500.0        # a device rating tighter than max_w
 d_absurd = decide(p_absurd, batt_w=1000.0, cap_w=CAP_W, reading=None,
-                  achievable_w=min(LIVE_MAX_W, DEV_MAX), max_hold_s=MAX_HOLD_S)
+                  achievable_w=min(LIVE_MAX_W, DEV_MAX), max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 r6 = resolve([Claim.limit("device", P_SAFETY, -DEV_MAX, DEV_MAX, "rating"),
               Claim.limit("supervised", P_SAFETY, -LIVE_MAX_W, LIVE_MAX_W, "max_w"),
               Claim.set("loop", P_LOOP, -200.0, "grid"),
@@ -461,7 +491,7 @@ print(f"    a real PeakStore on a missing volume: state={rd_broken.state}, "
 check("the real store answers NOT_OBSERVED rather than a peak of 0 W",
       rd_broken.state == NOT_OBSERVED and rd_broken.peak_w is None)
 d_broken = decide(p_over, batt_w=BATT_NOW, cap_w=CAP_W, reading=rd_broken,
-                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 print(f"    {d_broken.explain()}")
 check("AND THE GUARD STILL ENGAGES ON IT. An unreadable peak must not disarm "
       "the cap - 'no peak recorded' is precisely the reading that would, and it "
@@ -489,7 +519,7 @@ print("4. blindness: three ways a projection is not evidence")
 fresh = QuarterAverager(phases=1, max_hold_s=MAX_HOLD_S)
 p_fresh = PeakTracker.project(fresh, B)
 d_fresh = decide(p_fresh, batt_w=0.0, cap_w=CAP_W, reading=None,
-                 achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                 achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 print(f"    fresh averager: projected {p_fresh.projected_w:.0f} W, "
       f"block_start={p_fresh.block_start}; {d_fresh.explain()}")
 check("a fresh averager's projection is 0 W, i.e. comfortably under any "
@@ -517,7 +547,7 @@ RAILED = LIVE_MAX_W                          # the loop has wound to the rail
 is_frozen = looks_frozen(FREEZE_S + 1.0, -RAILED, LIVE_MAX_W,
                          FreezeWatchdogConfig(hold_s=FREEZE_S))
 d_frozen = decide(p_frozen, batt_w=-RAILED, cap_w=CAP_W, reading=None,
-                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR,
                   frozen=is_frozen)
 print(f"    meter stuck at -4000 W with the command at {-RAILED:+.0f} W: "
       f"projected {p_frozen.projected_w:.0f} W, coverage "
@@ -543,7 +573,7 @@ check("...and the same command NOT frozen is left alone, so the blind branch is
                            peakguard.claim(decide(
                                p_frozen, batt_w=-RAILED, cap_w=CAP_W,
                                reading=None, achievable_w=LIVE_MAX_W,
-                               max_hold_s=MAX_HOLD_S, frozen=False))
+                               max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR, frozen=False))
                            or Claim.limit("noop", P_PEAK)]).target_w,
            -RAILED, 1e-9))
 
@@ -554,7 +584,7 @@ p_gap = PeakTracker.project(gapped, B + timedelta(seconds=600))
 clean = averager_at(4200.0, 600.0)
 p_clean = PeakTracker.project(clean, B + timedelta(seconds=600))
 d_gap = decide(p_gap, batt_w=0.0, cap_w=CAP_W, reading=None,
-               achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+               achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 print(f"    a {GAP:.0f} s hole at 4200 W: uncovered {uncovered_s(p_gap):.0f} s, "
       f"projected {p_gap.projected_w:.0f} W vs {p_clean.projected_w:.0f} W with "
       f"no hole")
@@ -618,7 +648,7 @@ OLD = (p_held.partial_ws if hasattr(p_held, "partial_ws")
        else HELD * 300.0)   # acc, which the old form would still have had
 old_projected = (HELD * 300.0 + 0.0 * (QUARTER_S - 300.0)) / QUARTER_S
 d_true = decide(p_held, batt_w=0.0, cap_w=CAP_W, reading=None,
-                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S)
+                achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR)
 print(f"    same fixture: shipped projection {p_held.projected_w:.0f} W "
       f"(engaged={d_true.engaged}), the defaulted form's "
       f"{old_projected:.0f} W (would engage={old_projected > CAP_W})")
@@ -636,24 +666,55 @@ REPLAY = sorted((HERE / "scenarios").glob("p1-net-*.jsonl.gz"))
 check("the committed replay fixtures are present", len(REPLAY) >= 2)
 
 
-def replay(path, *, guarded: bool, cap_w=CAP_W, max_w=LIVE_MAX_W):
+def replay(path, *, guarded: bool, cap_w=CAP_W, max_w=LIVE_MAX_W, pack=None,
+           soc_floor=None):
     """Drive one capture through the real ingest, tracker and guard.
 
     See the module docstring for the model and why its baseline is pessimistic.
+
+    ⚠️ SAFETY-24's `pack` IS A SECOND MODEL, AND IT IS STATED HERE RATHER THAN
+    HIDDEN. The captures carry meter power only, so the pack is simulated:
+
+      pack = (usable_wh, start_soc_pct, bms_floor_pct)
+
+      * SoC falls by the DELIVERED discharge, integrated over the real telegram
+        timestamps - the same integral that already produces `wh`, so the two
+        cannot disagree;
+      * the BMS is modelled as a HARD CUT at `bms_floor_pct`: at or below it the
+        modelled battery delivers 0 W whatever the guard asks for. Without that,
+        the "before this card" run would be unphysical and its comparison
+        worthless - the BMS really does stop the pack, and the finding this card
+        answers is that it is then the ONLY thing that does;
+      * nothing recharges the pack. One day, one direction. That is pessimistic
+        in the same deliberate way the zero-baseline discharge is: it isolates
+        what the peak guard alone spends.
+
+    `pack=None` pins the SoC at SOC_OK and reproduces SAFETY-07's numbers
+    exactly, which is what parts 6's existing checks grade.
     """
     ing = P1Ingest(phases=1, max_age_s=MAX_HOLD_S)
-    store = fresh_store(f"{path.stem}-{'g' if guarded else 'u'}")
+    store = fresh_store(f"{path.stem}-{'g' if guarded else 'u'}"
+                        f"{'' if pack is None else f'-p{soc_floor:.0f}'}")
     tracker = PeakTracker(store, cap_w=cap_w)
     batt = 0.0                      # delivered discharge, W (positive)
     next_cycle = None
     graded_engaged = blind_engaged = saturated = cycles = 0
+    limited = at_bms = neg_floor = 0
     wh = 0.0
     prev_t = None
+    usable_wh, soc, bms = (None, SOC_OK, None) if pack is None else (
+        float(pack[0]), float(pack[1]), float(pack[2]))
+    floor_pct = SOC_FLOOR if soc_floor is None else float(soc_floor)
+    min_soc = soc
     for line in gzip.open(path, "rt", encoding="utf-8"):
         row = json.loads(line)
         t = datetime.fromisoformat(row["t"])
         if prev_t is not None:
-            wh += batt * (t - prev_t).total_seconds() / 3600.0
+            dwh = batt * (t - prev_t).total_seconds() / 3600.0
+            wh += dwh
+            if usable_wh:
+                soc = max(0.0, soc - 100.0 * dwh / usable_wh)
+                min_soc = min(min_soc, soc)
         prev_t = t
         ing.submit(sample(t, float(row["w"]) - batt))
         tracker.sync(ing)
@@ -663,7 +724,10 @@ def replay(path, *, guarded: bool, cap_w=CAP_W, max_w=LIVE_MAX_W):
         cycles += 1
         d = decide(PeakTracker.project(ing.averager, t),
                    batt_w=batt, cap_w=cap_w, reading=tracker.peak(t),
-                   achievable_w=max_w, max_hold_s=MAX_HOLD_S, frozen=False)
+                   achievable_w=max_w, max_hold_s=MAX_HOLD_S, soc=soc,
+                   soc_floor=floor_pct, frozen=False)
+        if d.floor_w is not None and d.floor_w < 0.0:
+            neg_floor += 1
         if d.engaged:
             (globals(), None)
             if d.blind:
@@ -671,15 +735,25 @@ def replay(path, *, guarded: bool, cap_w=CAP_W, max_w=LIVE_MAX_W):
             else:
                 graded_engaged += 1
             saturated += 1 if d.saturated else 0
+            limited += 1 if d.floor_limited else 0
+        if usable_wh and soc <= bms:
+            at_bms += 1
         if not guarded:
             continue
         batt = max(0.0, d.floor_w) if (d.engaged and d.floor_w is not None) else 0.0
+        # THE BMS, MODELLED. It is a real floor and it works - that is the whole
+        # point of stating the risk fairly - so the "before" world is not a pack
+        # discharged to nothing, it is a pack pinned at the BMS limit.
+        if usable_wh and soc <= bms:
+            batt = 0.0
     month = month_key(datetime.fromisoformat(json.loads(
         gzip.open(path, "rt", encoding="utf-8").readline())["t"]))
     return {
         "blocks": dict(store.blocks_in(month)), "cycles": cycles,
         "graded": graded_engaged, "blind": blind_engaged,
         "saturated": saturated, "wh": wh, "month": month,
+        "limited": limited, "at_bms": at_bms, "neg_floor": neg_floor,
+        "end_soc": soc, "min_soc": min_soc,
     }
 
 
@@ -872,7 +946,7 @@ check("...and the status page says NOT COVERED rather than 'idle' or a green "
 # Controller rather than left to flake. It is bounded at three attempts: a fourth
 # would mean something is wrong that is not a boundary.
 def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
-                     standing_w=None):
+                     standing_w=None, soc=55.0):
     """A real Controller driven one real cycle over a real over-limit quarter.
 
     ⚠️ THE LOAD IS DERIVED FROM WHERE IN THE QUARTER THE WALL CLOCK LANDS, and
@@ -886,7 +960,7 @@ def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
     for attempt in range(4):
         ctl, hs = built(db if attempt == 0 else Path(f"{db}.{attempt}"), opts,
                         store=_Store(store) if store is not None else None)
-        ctl.auto, ctl.soc, ctl.batt = True, 55.0, batt_w
+        ctl.auto, ctl.soc, ctl.batt = True, soc, batt_w
         ctl.dev_min, ctl.dev_max = -LIVE_MAX_W, LIVE_MAX_W
         if standing_w is not None:
             # The command STANDING ON THE WIRE, which is what B3 below needs to
@@ -911,6 +985,9 @@ def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
             ctl.cycle())
         g = ctl.peak_guard
         if g is not None and g.engaged and not g.blind:
+            # ⚠️ A FLOOR-LIMITED DECISION IS A LANDING, NOT A MISS. It is
+            # `engaged` and not `blind`, which is what this loop is waiting for;
+            # SAFETY-24's own fixtures below arrive here on purpose.
             return ctl, hs, net_w, remaining
         # Only a quarter boundary crossed between the last telegram and
         # `cycle()`'s own clock gets here. Bounded at four: a fifth would mean
@@ -1094,7 +1171,8 @@ check("B3: main.py sizes the floor from the MEASURED battery power, not from "
 # judged at a single point where they need not differ.
 _proj3 = PeakTracker.project(b3.p1.averager, datetime.now(timezone.utc))
 _kw = dict(cap_w=CAP_W, reading=b3.peak.peak(), achievable_w=LIVE_MAX_W,
-           max_hold_s=b3.p1.averager.max_hold_s)
+           max_hold_s=b3.p1.averager.max_hold_s, soc=SOC_OK,
+           soc_floor=SOC_FLOOR)
 _intent = _shipped_decide(_proj3, batt_w=STANDING, **_kw)
 check("one cycle of the intent form is exactly the delivered form plus the "
       "command standing on the wire - which is the whole defect in one line: "
@@ -1127,14 +1205,56 @@ check("...and the consequence is the wind-up part 1 demonstrates, now on the "
       and not b3.peak_guard.saturated)
 # Graded on the parsed call syntax too, so a rename cannot quietly reintroduce
 # it: the keyword main.py passes must be the measured attribute.
-_call = next(n for n in ast.walk(ast.parse(_mainsrc))
+# ⚠️ SELECTED BY QUALIFIED NAME, NOT BY BEING FIRST. This took the first
+# `.decide(` in main.py and asserted there was only one - which was true when
+# SAFETY-24 was written and STOPPED BEING TRUE when OPT-04 added
+# `arbitrage.decide(...)`. Grading "whichever .decide() the AST walk reaches
+# first" is exactly the fragility a reviewer flagged on SAFETY-07: it grades a
+# position, not the call. `peakguard.decide` is what this file is about, so name
+# it, and require exactly one of THAT.
+_peak_calls = [n for n in ast.walk(ast.parse(_mainsrc))
                if isinstance(n, ast.Call) and isinstance(n.func, ast.Attribute)
-             and n.func.attr == "decide")
+               and n.func.attr == "decide"
+               and isinstance(n.func.value, ast.Name)
+               and n.func.value.id == "peakguard"]
+_call = _peak_calls[0]
 _batt_src = ast.unparse(next(k.value for k in _call.keywords if k.arg == "batt_w"))
-print(f"    main.py's decide(batt_w=...) is `{_batt_src}`")
+_soc_src = ast.unparse(next(k.value for k in _call.keywords if k.arg == "soc"))
+print(f"    main.py's decide(batt_w=...) is `{_batt_src}`, decide(soc=...) is "
+      f"`{_soc_src}`")
 check("...and the call site says so in the source: the argument is the measured "
       "battery attribute, not the standing command and not the resolved target",
       _batt_src == "self.batt")
+# ⚠️ SAFETY-24, AND ON THE SAME SINGLE CALL SITE. This grader takes the FIRST
+# `.decide(` in main.py and reads a NAME rather than a value, so a second call
+# site - or a decoy - would defeat it; this card deliberately adds neither, and
+# extends the existing grader instead of writing a second one.
+check("...and `soc` is handed over as the MEASURED reading, bare. Not "
+      "`self.soc or 100`, not a `float(..., 100)`, not the maintenance floor: "
+      "a full battery is exactly the value that disarms SAFETY-24's floor, and "
+      "NOTES.md 4.4b records this project shipping that exact defaulting once",
+      _soc_src == "self.soc")
+check(f"...and main.py has exactly ONE `peakguard.decide(` call site (it has "
+      f"{len(_peak_calls)}), so the call graded above is unambiguously the "
+      f"shipped one. Other modules may call their own decide() - OPT-04's "
+      f"arbitrage.decide() does - and that must not silently move which call "
+      f"this grader reads",
+      len(_peak_calls) == 1)
+# ⚠️ AND WHICH KEY THE FLOOR COMES FROM, GRADED ON THE SOURCE. A mutation that
+# swapped `peak_soc_floor` for `maintenance_soc_floor` SURVIVED every
+# behavioural check in this file, because the two defaults are close enough that
+# no fixture separated them - which is exactly the coupling the card forbids and
+# exactly the kind of survivor a value-based check cannot see. This grades the
+# NAME, and part 9 below now also separates them behaviourally.
+_floor_src = ast.unparse(next(k.value for k in _call.keywords
+                              if k.arg == "soc_floor")).replace("'", '"')
+print(f"    main.py's decide(soc_floor=...) is `{_floor_src}`")
+check("...and the floor comes from `peak_soc_floor`, defaulted from the ONE "
+      "mirror - not from `maintenance_soc_floor` (a drain target, not a spend "
+      "limit) and not from a literal, which would be CFG-03's fourth site",
+      '"peak_soc_floor"' in _floor_src
+      and "maintenance_soc_floor" not in _floor_src
+      and 'PEAK_OPTION_DEFAULTS["peak_soc_floor"]' in _floor_src)
 
 # SAFETY-24 must be pointed at from the module that needs it, not only from a
 # review thread - a ticket nobody can find from the code is a ticket nobody
@@ -1147,10 +1267,20 @@ check("peakguard.py names SAFETY-24, the missing SoC backstop on the forced "
 # CFG-03: no fourth defaults site.
 cfg = (HERE / "config.yaml").read_text(encoding="utf-8")
 val = (HERE / "app" / "validate.py").read_text(encoding="utf-8")
-check("no new option was added: config.yaml names no peak-guard key, and "
+# ⚠️ REWRITTEN BY SAFETY-24, BECAUSE IT IS NO LONGER TRUE AS WRITTEN. SAFETY-07
-      "§14's kW/W trap `capacity_peak_limit_kw` stays declined",
+# added no option and this check said so. This card adds TWO and says which -
-      "peak_guard" not in cfg and "capacity_peak_limit_kw" not in cfg
+# leaving the old sentence in place while the file it reads has grown two keys
-      and "peak_shave" not in cfg)
+# would be a green line asserting the opposite of the diff. What is still
+# refused is a THIRD: §14's kW/W trap stays declined, and no key beyond the two
+# named ones exists.
+_peak_keys = sorted(k for k in ("peak_guard", "peak_shave",
+                                "capacity_peak_limit_kw")
+                    if k in cfg)
+check("SAFETY-24 adds exactly the two keys it names and no more: §14's kW/W "
+      "trap `capacity_peak_limit_kw` stays declined, and no speculative "
+      "`peak_guard`/`peak_shave` block appeared beside it",
+      _peak_keys == []
+      and sorted(PEAK_OPTION_DEFAULTS) == ["bms_soc_floor", "peak_soc_floor"])
 # Graded on the parsed call syntax, not on the text: the module docstring names
 # `peak_cap_w` while arguing that it does not read it, so a grep would be
 # satisfied by deleting the explanation and would fail on writing one.
@@ -1161,11 +1291,14 @@ _getters = [n for n in ast.walk(ast.parse(src))
             if isinstance(n, ast.Call) and isinstance(n.func, ast.Attribute)
             and n.func.attr == "get"]
 print(f"    peakguard.py makes {len(_getters)} options-style `.get()` calls")
-check("peakguard.py reads no option of its own: it makes no `.get()` call at "
+check("peakguard.py still READS no option: it makes no `.get()` call at all "
-      "all and takes `cap_w` as an argument. CFG-03's three defaults sites are "
+      "and takes `cap_w`, `soc` and `soc_floor` as arguments. CFG-03's three "
-      "config.yaml's `options:`, config.yaml's `schema:` and main.py's literal "
+      "defaults sites are config.yaml's `options:`, config.yaml's `schema:` "
-      "fallbacks - this card adds no fourth",
+      "and main.py's fallbacks; PEAK_OPTION_DEFAULTS is a MIRROR of the first, "
-      not _getters and "cap_w" in _DECIDE_ARGS)
+      "TARIFF-02-style, not a fourth site - it is what main.py and validate.py "
+      "read INSTEAD of typing literals",
+      not _getters and "cap_w" in _DECIDE_ARGS and "soc" in _DECIDE_ARGS
+      and "soc_floor" in _DECIDE_ARGS)
 # And the fallback in main.py must equal the shipped default, for the reason
 # test_validate.py's CFG-03 block spells out at length: the two diverging is a
 # live defect in this repo for `maintenance_charge_w`, and it is not to be
@@ -1182,7 +1315,494 @@ check("...and every literal fallback for peak_cap_w in main.py equals the "
 
 # ==============================================================================
 print()
-print("8. mutation: what defeats this guard, and which check bites")
+print("8. SAFETY-24: the energy floor under the forced discharge")
+
+# ⚠️ THE STIMULUS FIRST, AND IT IS NOT DEGENERATE. Everything below is graded on
+# a quarter that GENUINELY WANTS A FORCED DISCHARGE - `wanted > 0` - because the
+# state of charge governs nothing on a cycle where the guard was never going to
+# discharge. A check placed on a quiet quarter would pass with the gate removed,
+# with the gate inverted, and with the gate reading the wrong sensor.
+a_hungry = averager_at(CEIL + 900.0, 600.0)
+p_hungry = PeakTracker.project(a_hungry, B + timedelta(seconds=600))
+WANTED = BATT_NOW + excess_w(p_hungry, CEIL)
+print(f"    the stimulus: a quarter projecting {p_hungry.projected_w:.0f} W "
+      f"against a {CEIL:.0f} W ceiling with "
+      f"{QUARTER_S - p_hungry.elapsed_s:.0f} s left; a forced discharge of "
+      f"{WANTED:+.0f} W is what would hold it")
+check("the stimulus really does want a forced discharge, so the SoC is a "
+      "quantity that decides something here", WANTED > 0.0)
+
+# --- the predicate, which is the ONE place the question is answered ----------
+PERMITS = discharge_permitted(SOC_OK, SOC_FLOOR)
+AT = discharge_permitted(SOC_FLOOR, SOC_FLOOR)
+UNDER = discharge_permitted(SOC_FLOOR - 1.0, SOC_FLOOR)
+UNREAD = discharge_permitted(None, SOC_FLOOR)
+NOFLOOR = discharge_permitted(SOC_OK, None)
+print(f"    discharge_permitted: {SOC_OK:.0f} % -> {PERMITS!r}")
+print(f"                         {SOC_FLOOR:.0f} % (exactly at) -> {AT!r}")
+print(f"                         None (unreadable) -> {UNREAD!r}")
+check("a pack above the floor may be discharged", PERMITS is None)
+check("...a pack AT the floor may not - `<=`, not `<`. Permitting one more "
+      "cycle at the floor would make the floor mean 'one cycle below the "
+      "floor', which is the whole quantity this option names",
+      AT == FLOOR_AT_SOC_FLOOR and UNDER == FLOOR_AT_SOC_FLOOR)
+check("...an UNREADABLE SoC is refused, and refused with its OWN reason. A "
+      "failed read is not an observation, and a full battery is exactly the "
+      "value that would disarm this floor",
+      UNREAD == FLOOR_SOC_UNREADABLE and UNREAD != AT)
+check("...and no configured floor is not permission either", NOFLOOR is not None)
+# THE DISARMING ALTERNATIVE, COMPUTED RATHER THAN DESCRIBED. `float(soc or 100)`
+# is the shape NOTES.md 4.4b records the stage-5 loop actually shipping.
+check("...and the defaulting form that was ACTUALLY shipped once in this "
+      "project - reading a missing SoC as a full battery - would have permitted "
+      "it, so this is a live direction and not a hypothetical",
+      discharge_permitted(float(None or 100), SOC_FLOOR) is None)
+
+# --- the decision -----------------------------------------------------------
+d_ok = decide(p_hungry, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
+              achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK,
+              soc_floor=SOC_FLOOR)
+d_lim = decide(p_hungry, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
+               achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+               soc=SOC_FLOOR, soc_floor=SOC_FLOOR)
+d_unread = decide(p_hungry, batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
+                  achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=None,
+                  soc_floor=SOC_FLOOR)
+print(f"    with battery:  {d_ok.explain()}")
+print(f"    at the floor:  {d_lim.explain()}")
+check("with battery to spare the guard sizes the forced discharge exactly as "
+      "SAFETY-07 always did - this card changes nothing above the floor",
+      d_ok.engaged and not d_ok.floor_limited and near(d_ok.floor_w, WANTED, 1e-6))
+check("at the floor it STOPS, and the floor it files is 0 W - not the discharge "
+      "it wanted, and not a negative number",
+      d_lim.engaged and d_lim.floor_limited and near(d_lim.floor_w, 0.0))
+check("...and it REPORTS being floor-limited rather than silently under-"
+      "shaving: the decision carries the flag, the reason it bound, the SoC it "
+      "read and the floor it read",
+      d_lim.floor_limited and d_lim.soc_floor_reason == FLOOR_AT_SOC_FLOOR
+      and near(d_lim.soc, SOC_FLOOR) and near(d_lim.soc_floor, SOC_FLOOR))
+check("...and it still says what it WOULD have taken, so the under-shave is a "
+      "number rather than a silence",
+      near(d_lim.wanted_w, WANTED, 1e-6) and d_lim.wanted_w > d_lim.floor_w)
+check("...and its one-line explanation tells the operator the consequence in "
+      "the words that matter - the quarter is going over the ceiling",
+      "FLOOR-LIMITED" in d_lim.explain()
+      and "WILL GO OVER THE CEILING" in d_lim.explain()
+      and f"{CEIL:.0f} W" in d_lim.explain())
+check("an unreadable SoC lands in the same branch, with the OTHER reason - so "
+      "an operator reading one line can tell a flat battery from a dead sensor",
+      d_unread.floor_limited and near(d_unread.floor_w, 0.0)
+      and d_unread.soc_floor_reason == FLOOR_SOC_UNREADABLE
+      and d_unread.soc is None)
+check("floor-limited and saturated are MUTUALLY EXCLUSIVE, by construction: the "
+      "branch returns before the achievable_w clamp that sets `saturated`, so "
+      "the two notifications can never both fire on one cycle",
+      not d_lim.saturated and not d_unread.saturated)
+
+# --- and NOT graded where it is degenerate ----------------------------------
+# The same empty pack on a quarter that is UNDER the ceiling. A gate placed one
+# line earlier would report FLOOR-LIMITED here - on a quiet afternoon, over a
+# guard that was never going to discharge - and an operator who is told the peak
+# will be exceeded on a quarter that is nowhere near it stops reading the
+# notification that matters.
+d_quiet = decide(PeakTracker.project(averager_at(500.0, 450.0),
+                                     B + timedelta(seconds=450)),
+                 batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
+                 achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                 soc=SOC_FLOOR - 5.0, soc_floor=SOC_FLOOR)
+print(f"    an EMPTY pack on a quiet quarter: {d_quiet.explain()}")
+check("an empty pack on a quarter that does not need shaving is IDLE, not "
+      "floor-limited. The SoC is only graded where a forced discharge is "
+      "actually being asked for - grading it earlier would raise the alarm on "
+      "every quiet cycle of the day",
+      not d_quiet.engaged and not d_quiet.floor_limited
+      and d_quiet.floor_w is None)
+# And the BLIND branch is untouched: it never forces a discharge, so there is
+# nothing for an energy floor to bound there.
+d_blind_low = decide(p_frozen, batt_w=-RAILED, cap_w=CAP_W, reading=None,
+                     achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                     soc=SOC_FLOOR - 5.0, soc_floor=SOC_FLOOR, frozen=True)
+check("...and an empty pack does not disturb the BLIND branch either: SAFETY-"
+      "18's cut is still a 0 W floor, still blocks charging, and is still not "
+      "reported as an energy problem",
+      d_blind_low.engaged and near(d_blind_low.floor_w, 0.0)
+      and d_blind_low.blind == BLIND_FROZEN and not d_blind_low.floor_limited)
+
+# --- the claim, through the real arbiter ------------------------------------
+lc = peakguard.claim(d_lim)
+print(f"    floor-limited claim: {lc.source} {lc.kind} lo={lc.lo:.0f} "
+      f"hi={lc.hi} reason={lc.reason!r}")
+r_charge = resolve(SAFE + [Claim.set("loop", P_LOOP, -1500.0, "grid"), lc])
+r_disch = resolve(SAFE + [Claim.set("loop", P_LOOP, 1800.0, "grid"), lc])
+r_stop = resolve(SAFE + [Claim.set("safety", P_SAFETY, 0.0, "stopped"), lc])
+print(f"    loop wants to charge 1500 W: {r_charge.explain()}")
+print(f"    loop wants to discharge 1800 W: {r_disch.explain()}")
+check("a floor-limited guard STILL blocks charging - 0 W is one-directional, "
+      "it can only ever lower delivered offtake, and adding import in the "
+      "quarter that sets the bill is the one thing it must not permit",
+      near(r_charge.target_w, 0.0) and not r_charge.contradiction)
+check("...and it does NOT pull the loop off a discharge it is already doing. A "
+      "`lo` limit is structurally incapable of capping discharge, which is why "
+      "the action here is 0 W and never a negative floor",
+      near(r_disch.target_w, 1800.0, 1e-9))
+check("...and every P_SAFETY stop still outranks it. This is an ENERGY bound, "
+      "not a trip: 11.2's table is unchanged by this card",
+      near(r_stop.target_w, 0.0) and not r_stop.contradiction)
+check("...and its arbiter reason names the SoC floor rather than reusing "
+      "'blind' or 'quarter peak', so the one line an operator reads tells the "
+      "three 0 W states apart", lc.reason == "SoC floor"
+      and peakguard.claim(d_ok).reason == "quarter peak")
+
+# --- THE PROPERTY THE WHOLE SHAPE RESTS ON: no negative floor, ever ----------
+# A `lo` limit is incapable of capping discharge or export only while it is
+# non-negative. If this card could produce `lo < 0` it would have broken 9.1 as
+# a property of the object, and the guard would be capping the very thing it is
+# forbidden to cap. Swept rather than argued.
+SWEEP_NEG = SWEEP_BOTH = SWEEP_N = 0
+SWEEP_HI = True
+for load in (0.0, CEIL - 500.0, CEIL, CEIL + 300.0, CEIL + 3000.0,
+             LIVE_MAX_W * 3):
+    for elapsed in (30.0, 450.0, 870.0):
+        _pr = PeakTracker.project(averager_at(load, elapsed),
+                                  B + timedelta(seconds=elapsed))
+        for bw in (-2000.0, 0.0, 400.0, 4000.0):
+            for sc in (None, 0.0, BMS_FLOOR, SOC_FLOOR, SOC_FLOOR + 0.5, 100.0):
+                for fl in (SOC_FLOOR, BMS_FLOOR + 1.0, 55.0):
+                    _d = decide(_pr, batt_w=bw, cap_w=CAP_W, reading=None,
+                                achievable_w=LIVE_MAX_W,
+                                max_hold_s=MAX_HOLD_S, soc=sc, soc_floor=fl)
+                    SWEEP_N += 1
+                    if _d.floor_w is not None and _d.floor_w < 0.0:
+                        SWEEP_NEG += 1
+                    if _d.floor_limited and _d.saturated:
+                        SWEEP_BOTH += 1
+                    _c = peakguard.claim(_d)
+                    if _c is not None and not (isinf(_c.hi) and _c.hi > 0):
+                        SWEEP_HI = False
+print(f"    swept {SWEEP_N} (load x elapsed x battery x SoC x floor) "
+      f"combinations, SoC included: {SWEEP_NEG} negative floors, "
+      f"{SWEEP_BOTH} decisions both floor-limited and saturated")
+check(f"NOT ONE of the {SWEEP_N} combinations produces a negative floor. That "
+      f"is 9.1's 'discharge and export are never capped by the peak guard' as a "
+      f"property of the object, and SAFETY-24 preserves it - the only two "
+      f"values floor_w takes are 0.0 and a positive min(wanted, achievable)",
+      SWEEP_NEG == 0 and SWEEP_N > 600)
+check("...and `hi` stays +inf on every claim any of them files",
+      SWEEP_HI)
+check("...and no combination is both floor-limited and saturated, so the two "
+      "notifications are exclusive on measured inputs and not merely by reading "
+      "the code", SWEEP_BOTH == 0)
+
+# --- TEST-14: a required field must not quietly gain a default --------------
+# ⚠️ PORTED AS A SCAN, NOT HAND-WRITTEN PER FIELD. TEST-14 is open because an
+# outcome type's required field gained a default in three separate files and no
+# check noticed. The pinned sets below go red if ANY field or argument moves
+# between required and defaulted - including a future one nobody has thought of
+# - which is the whole difference between a scan and a case.
+_sig = inspect.signature(decide)
+_required_kw = {n for n, prm in _sig.parameters.items()
+                if prm.kind is prm.KEYWORD_ONLY and prm.default is prm.empty}
+print(f"    decide() required keyword-only arguments: {sorted(_required_kw)}")
+check("`soc` and `soc_floor` are REQUIRED keyword-only arguments of decide() "
+      "with no default. A default on either is TEST-14's exact shape and would "
+      "be the quiet fallback this card exists to remove - and a default on "
+      "`soc_floor` would additionally be CFG-03's fourth defaults site",
+      _required_kw == {"batt_w", "cap_w", "reading", "achievable_w", "soc",
+                       "soc_floor"})
+_req_fields = tuple(f.name for f in dataclasses.fields(PeakDecision)
+                    if f.default is dataclasses.MISSING
+                    and f.default_factory is dataclasses.MISSING)
+print(f"    PeakDecision fields with no default: {list(_req_fields)}")
+check("...and PeakDecision's required fields are unchanged by this card: the "
+      "four SAFETY-07 pinned, and the SAFETY-24 additions are genuinely "
+      "optional reporting rather than required fields handed a default",
+      _req_fields == ("engaged", "floor_w", "ceiling_w", "ceiling_from"))
+
+
+# ==============================================================================
+print()
+print("9. the exhausting replay (AC 4), and the startup refusal")
+
+# ⚠️ THE PACK IS SIZED FROM THE MEASUREMENT, NOT PICKED. `WH_07` is what the
+# guard actually asks for on 2026-08-20 - re-derived from the committed capture
+# on every run, never quoted - and the modelled pack is then chosen so the energy
+# between the start and the EMS floor is ONE THIRD of it. That makes "a quarter
+# that would exhaust the pack" true by construction of the measurement rather
+# than by a number typed into this file: the day wants three times what the pack
+# has to give above the floor, so it must run out, and without an EMS floor it
+# must run through the BMS one too.
+BAD = [pth for pth in REPLAY if "2026-08-20" in pth.name][0]
+WH_BAD = replay(BAD, guarded=True)["wh"]
+START_SOC = SOC_FLOOR + (SOC_FLOOR - BMS_FLOOR)
+USABLE_WH = 100.0 * (WH_BAD / 3.0) / (START_SOC - SOC_FLOOR)
+PACK = (USABLE_WH, START_SOC, BMS_FLOOR)
+# How far past the floor one cycle at the rail can carry the pack before the
+# next decision sees it. DERIVED from the cycle and the modelled pack, because a
+# tolerance typed as a constant is a tolerance that stops meaning anything.
+OVERSHOOT_PP = 100.0 * (LIVE_MAX_W * CYCLE_S / 3600.0) / USABLE_WH
+print(f"    the guard's measured appetite on {BAD.name}: {WH_BAD:.0f} Wh")
+print(f"    modelled pack: {USABLE_WH:.0f} Wh usable, starting at "
+      f"{START_SOC:.0f} %, BMS cut at {BMS_FLOOR:.0f} %, EMS floor at "
+      f"{SOC_FLOOR:.0f} %")
+print(f"      -> {(START_SOC - SOC_FLOOR) / 100.0 * USABLE_WH:.0f} Wh above the "
+      f"EMS floor, {(START_SOC - BMS_FLOOR) / 100.0 * USABLE_WH:.0f} Wh above "
+      f"the BMS one - against {WH_BAD:.0f} Wh of appetite; one cycle at the "
+      f"rail is {OVERSHOOT_PP:.2f} pp of this pack")
+check("the fixture is a pack this day genuinely exhausts, and that is derived "
+      "from the day's own measured appetite rather than asserted: the energy "
+      "above the BMS cut-out is less than the guard wants",
+      (START_SOC - BMS_FLOOR) / 100.0 * USABLE_WH < WH_BAD)
+
+# TWO WORLDS, SAME PACK, SAME CAPTURE.
+#   BEFORE: the EMS floor set to the BMS cut-out - i.e. the BMS is the sole
+#           energy backstop, which is precisely what SAFETY-07 shipped.
+#   AFTER:  the EMS floor as config.yaml ships it.
+BEFORE = replay(BAD, guarded=True, pack=PACK, soc_floor=BMS_FLOOR)
+AFTER = replay(BAD, guarded=True, pack=PACK, soc_floor=SOC_FLOOR)
+print(f"    BEFORE (BMS is the only backstop): ends at {BEFORE['end_soc']:.1f} %"
+      f", low-water {BEFORE['min_soc']:.1f} %, {BEFORE['wh']:.0f} Wh out, "
+      f"{BEFORE['at_bms']} guard cycles spent AT the BMS limit, "
+      f"{BEFORE['limited']} floor-limited")
+print(f"    AFTER  (peak_soc_floor {SOC_FLOOR:.0f} %):  ends at "
+      f"{AFTER['end_soc']:.1f} %, low-water {AFTER['min_soc']:.1f} %, "
+      f"{AFTER['wh']:.0f} Wh out, {AFTER['at_bms']} cycles at the BMS limit, "
+      f"{AFTER['limited']} floor-limited")
+check("BEFORE: the day really does take the pack to the BMS cut-out and hold it "
+      "there. That is the finding this card answers - not a pack destroyed, a "
+      "pack repeatedly parked at its own protection with no EMS-side record of "
+      "why", BEFORE["min_soc"] <= BMS_FLOOR + 1e-9 and BEFORE["at_bms"] > 0)
+check("AFTER: the forced discharge STOPS AT THE CONFIGURED FLOOR - to within "
+      "the one cycle of overshoot the 15 s tick allows, derived above and not "
+      "typed - and the pack never reaches the BMS limit at all. That is AC 1, "
+      "replayed rather than reasoned about",
+      AFTER["min_soc"] >= SOC_FLOOR - OVERSHOOT_PP and AFTER["at_bms"] == 0
+      and AFTER["min_soc"] > BMS_FLOOR + 1.0)
+check("...and it does not merely stop, it SAYS SO: floor-limited cycles are "
+      "counted off the decisions themselves, so the under-shave is reported "
+      "rather than silent", AFTER["limited"] > 0)
+# ⚠️ WHAT "BEFORE" IS AND IS NOT. It is the shipped code with the EMS floor set
+# equal to the BMS cut-out, which reproduces the pre-card ENERGY trajectory
+# exactly - the pack drains to the BMS and the BMS is the only thing that stops
+# it. What it does not reproduce is the silence: pre-card there was no gate to
+# report at all, whereas this run reports one at the BMS limit, by which point
+# the pack is already there. The trajectory is the thing being compared.
+check("...and the two worlds differ in the trajectory, not merely in a flag: "
+      "before, every floor-limited cycle happens with the pack ALREADY at the "
+      "BMS limit; after, none of them do",
+      BEFORE["at_bms"] > 0 and AFTER["at_bms"] == 0)
+# THE DERIVED VERDICT: the energy the card withholds is exactly the energy
+# between the two floors. Not "less", not "a bit" - the difference in Wh equals
+# the difference in percentage points times the pack, to within one cycle.
+GAP_WH = (SOC_FLOOR - BMS_FLOOR) / 100.0 * USABLE_WH
+TOL = 2.0 * LIVE_MAX_W * CYCLE_S / 3600.0   # one cycle of overshoot per run
+print(f"    energy withheld: {BEFORE['wh'] - AFTER['wh']:.1f} Wh, against "
+      f"{GAP_WH:.1f} Wh between the two floors (tolerance {TOL:.1f} Wh = one "
+      f"cycle of overshoot at the rail in each of the two runs)")
+check("the energy this card withholds IS the energy between the two floors, to "
+      "within one cycle at the rail - so the floor is doing the arithmetic it "
+      "claims and is not merely correlated with doing less",
+      abs((BEFORE["wh"] - AFTER["wh"]) - GAP_WH) <= TOL)
+check("...and no cycle in either world files a negative floor, on real "
+      "captured data and not only on the synthetic sweep",
+      BEFORE["neg_floor"] == 0 and AFTER["neg_floor"] == 0)
+# THE HONEST HALF. Stopping costs money, and the check says how much rather than
+# looking away from it.
+_ub = max(BEFORE["blocks"].values())
+_ab = max(AFTER["blocks"].values())
+print(f"    the price of the floor: worst quarter {_ub:.0f} W before, "
+      f"{_ab:.0f} W after - a floor-limited guard shaves LESS, on purpose, and "
+      f"the operator is told so")
+check("stopping at the floor costs peak shaving, and this file says so out "
+      "loud rather than reporting only the SoC it saved: the worst quarter is "
+      "no better with the floor in place", _ab >= _ub - 1e-6)
+
+# --- the wiring: one real cycle on an empty pack -----------------------------
+# ⚠️ `maintenance_soc_floor` IS SET, AND SET TO A VALUE THAT WOULD FLIP THE
+# ANSWER. The pack sits one point under `peak_soc_floor` and well ABOVE the
+# maintenance floor, so a controller that read the maintenance key would come
+# out NOT limited here. Without this the two keys are indistinguishable on every
+# fixture in this file - a mutation swapping them survived until it was added.
+MAINT_LOW = 5
+c24, hass24, NET24, _ = wired_over_limit(
+    TMP / "soc24.db", LIVE_MAX_W * 0.3, soc=SOC_FLOOR - 1.0,
+    opts={"maintenance_soc_floor": MAINT_LOW})
+check(f"the fixture separates the two floors: the pack at {SOC_FLOOR - 1:.0f} % "
+      f"is under peak_soc_floor {SOC_FLOOR:.0f} % and over "
+      f"maintenance_soc_floor {MAINT_LOW} %, so reading the wrong key gives the "
+      f"wrong answer here", MAINT_LOW < SOC_FLOOR - 1.0 < SOC_FLOOR)
+print(f"    a real cycle over a {NET24:.0f} W quarter with the pack at "
+      f"{SOC_FLOOR - 1.0:.0f} %: {c24.peak_guard.explain()}")
+check("the REAL Controller reaches the floor-limited branch, so main.py hands "
+      "decide() a state of charge at all", c24.peak_guard.floor_limited)
+check("...and the number written to the inverter is not a forced discharge - "
+      "the pack is not spent for money below the floor",
+      hass24.writes and hass24.writes[-1] >= -1e-6
+      and hass24.writes[-1] <= c24.peak_guard.wanted_w)
+check("...and the operator is TOLD THE PEAK WILL BE EXCEEDED, exactly once, "
+      "with its own notification id - AC 2, and the reason failing to shave "
+      "must not be silent",
+      hass24.notifications.count("goodwe_peak_soc_floor") == 1
+      and "goodwe_peak_saturated" not in hass24.notifications)
+asyncio.get_event_loop_policy().new_event_loop().run_until_complete(c24.cycle())
+check("...once per episode, not once per cycle - a quarter of an hour of "
+      "identical cards is how an operator learns to dismiss the one that "
+      "mattered", hass24.notifications.count("goodwe_peak_soc_floor") == 1)
+rows24 = [r for r in c24.checks() if "peak guard" in r["text"].lower()]
+print("    status row: " + (rows24[0]["text"] if rows24 else "(none)"))
+check("the status page carries exactly one peak-guard row and it is NOT ok - "
+      "the money is going to be spent and a human is the only actuator left",
+      len(rows24) == 1 and not rows24[0]["ok"]
+      and "FLOOR-LIMITED" in rows24[0]["text"])
+check("...and it reaches the action log too", any("FLOOR-LIMITED" in e
+                                                  for e in c24.events))
+# A missing SoC sensor, through the same real cycle. `inputs_ok` stops the loop
+# at 0 W in that state, so the guard's own answer is what is graded here.
+d_nosoc = decide(p_hungry, batt_w=0.0, cap_w=CAP_W, reading=None,
+                 achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                 soc=None, soc_floor=SOC_FLOOR)
+check("decide() handed soc=None answers floor-limited rather than a full "
+      "battery - the whole 'a failed read is not an observation' rule, on the "
+      "one input where the disarming value is the plausible one",
+      d_nosoc.floor_limited and not d_nosoc.saturated)
+# ⚠️ REVIEW-FOUND, AND THE CLAIM ABOVE USED TO BE WIDER THAN ITS CHECK. It read
+# "a CONTROLLER whose SoC entity does not answer hands decide() None" while
+# calling decide() directly and driving no Controller - so a reviewer could
+# insert `self.soc = 100.0 if self.soc is None else self.soc` immediately above
+# main.py's decide() call, which is the exact `float(soc or 100)` defaulting
+# discharge_permitted()'s own docstring forbids, and every check here stayed
+# green. The wiring property is STRONGER than the one that was claimed, and this
+# is it: a Controller with no SoC never reaches the guard at all, because
+# `inputs_ok` is False and cycle() returns at the safety stop first. Graded on
+# the SERVICE CALL - decide() is spied - rather than on its arguments, so a
+# defaulted value cannot satisfy it.
+_nosoc_ctl, _nosoc_hass = built(TMP / "nosoc.db")
+_nosoc_ctl.auto, _nosoc_ctl.soc, _nosoc_ctl.batt = True, None, 0.0
+_nosoc_ctl.dev_min, _nosoc_ctl.dev_max = -LIVE_MAX_W, LIVE_MAX_W
+_nosoc_now = datetime.now(timezone.utc)
+_nosoc_blk = datetime.fromtimestamp(
+    int(_nosoc_now.timestamp() // QUARTER_S) * QUARTER_S, timezone.utc)
+for _i in range(0, int((_nosoc_now - _nosoc_blk).total_seconds()) + 1, 5):
+    _nosoc_ctl.p1.submit(sample(_nosoc_blk + timedelta(seconds=_i), CAP_W * 2))
+_nosoc_ctl.grid = CAP_W * 2
+_nosoc_seen = []
+_nosoc_real = peakguard.decide
+try:
+    peakguard.decide = lambda *a, **k: (_nosoc_seen.append(k.get("soc")),
+                                        _nosoc_real(*a, **k))[1]
+    asyncio.get_event_loop_policy().new_event_loop().run_until_complete(
+        _nosoc_ctl.cycle())
+finally:
+    peakguard.decide = _nosoc_real
+print(f"    a Controller with no SoC: inputs_ok={_nosoc_ctl.inputs_ok}, "
+      f"decide() called {len(_nosoc_seen)} time(s), target "
+      f"{_nosoc_ctl.target:+.0f} W")
+check("and a Controller whose SoC entity does not answer never reaches the "
+      "guard AT ALL - `inputs_ok` is False, cycle() stops at the safety claim, "
+      "and decide() is not called. A defaulting line above the call site "
+      "therefore cannot disarm this floor, which is a stronger guarantee than "
+      "handing decide() a None would be",
+      not _nosoc_ctl.inputs_ok and not _nosoc_seen
+      and abs(_nosoc_ctl.target) < 1e-9 and _nosoc_ctl.peak_guard is None)
+
+# --- the startup refusal, in CFG-01 / MAINT-04's manner ----------------------
+def opts24(**kw):
+    """Otherwise-startable options, so the ONLY thing under test is rule 8."""
+    base = {"setpoint_entity": "number.sp", "meter_source": "off",
+            "meter_entity": "sensor.grid", "max_w": 2000,
+            "meter_phases": 1, "meter_max_age_s": 30, "sign_disagree_w": 300,
+            "maintenance_charge_w": 2000,
+            "peak_soc_floor": PEAK_OPTION_DEFAULTS["peak_soc_floor"],
+            "bms_soc_floor": PEAK_OPTION_DEFAULTS["bms_soc_floor"]}
+    base.update(kw)
+    return base
+
+
+BASE_OK = validate_startup_config(opts24())
+check("the SHIPPED pair starts - a validator that refuses config.yaml's own "
+      "defaults is a validator nobody keeps", BASE_OK == [])
+
+
+def rule8(problems):
+    return [x for x in problems if "bms_soc_floor" in x]
+
+
+below = rule8(validate_startup_config(opts24(peak_soc_floor=BMS_FLOOR - 5)))
+equal = rule8(validate_startup_config(opts24(peak_soc_floor=BMS_FLOOR)))
+above = rule8(validate_startup_config(opts24(peak_soc_floor=BMS_FLOOR + 1)))
+junk = validate_startup_config(opts24(peak_soc_floor="soon"))
+print(f"    refusal at {BMS_FLOOR - 5:.0f} %: {below[0][:96] if below else '(none)'}...")
+check("a floor BELOW the pack's own cut-out is refused at startup, in CFG-01 / "
+      "MAINT-04's manner - the operator states a bound, the BMS enforces a "
+      "different one, and nothing would say which won", len(below) == 1)
+check("...and so is a floor EXACTLY AT it, which is the interesting case: equal "
+      "buys zero margin, so it can never be the thing that stops the discharge "
+      "and the status page would report a backstop that cannot bind. Rule 6 "
+      "permits equality because equality there leaves one working point; here "
+      "it leaves none", len(equal) == 1)
+check("...while one point above is accepted, so this refuses the disarmed case "
+      "only and not 'close to the limit'", above == [])
+check("...and the refusal NAMES BOTH NUMBERS and the shipped default, so the "
+      "operator can act on it without reading the source",
+      f"{BMS_FLOOR:.0f} %" in below[0]
+      and f"{BMS_FLOOR - 5:.0f} %" in below[0]
+      and f"{PEAK_OPTION_DEFAULTS['peak_soc_floor']:.0f} %" in below[0])
+check("...and a non-numeric floor is refused rather than defaulted, for the "
+      "reason every read in this file is: a value that cannot be parsed is not "
+      "an observation of anything",
+      any("must both be numbers" in x for x in junk))
+# ⚠️ AND IT IS NOT SCOPED TO ANYTHING. Rule 6's comment gives the argument: a
+# contradictory pair is contradictory whether or not the feature is switched on,
+# and scoping it leaves the trap armed for the one operator action that cannot
+# be expected to change what a floor means.
+check("...and the rule is not scoped to meter_source or to any enable flag - "
+      "the pair is wrong on a P1 install too, and 'turn P1 on' is not an action "
+      "that should change what a SoC floor means",
+      len(rule8(validate_startup_config(opts24(
+          peak_soc_floor=BMS_FLOOR - 5, meter_source="ha_signed",
+          p1_net_entity="sensor.net")))) == 1)
+
+# --- CFG-03: the mirror, pinned to config.yaml -------------------------------
+# TARIFF-02's pattern exactly - and pinned by READING the shipped file, not by
+# transcribing it, which is the only version of this check that can catch drift.
+_found24 = {k: read_option(k) for k in PEAK_OPTION_DEFAULTS}
+print(f"    config.yaml ships {_found24}, peakguard mirrors "
+      f"{dict(PEAK_OPTION_DEFAULTS)}")
+check("every SAFETY-24 option is shipped in config.yaml's options: block",
+      all(v is not None for v in _found24.values()))
+check("...and each shipped default equals PEAK_OPTION_DEFAULTS, the ONE in-code "
+      "mirror - TARIFF-02's move, so this card adds no fourth defaults site",
+      all(float(_found24[k]) == float(v)
+          for k, v in PEAK_OPTION_DEFAULTS.items()))
+_schema24 = [k for k in PEAK_OPTION_DEFAULTS if read_schema_max(k) is not None]
+check("...and both are in the schema: block too, or the Supervisor drops the "
+      "option and the add-on silently runs on the mirror instead of the "
+      "operator's value", sorted(_schema24) == sorted(PEAK_OPTION_DEFAULTS))
+_val_src = (HERE / "app" / "validate.py").read_text(encoding="utf-8")
+check("...and validate.py takes its fallbacks from that same mirror rather than "
+      "typing literals - which is the divergence its own rule 6 documents "
+      "(maintenance_charge_w 2000 there, 2500 in main.py), refused a second "
+      "outing here",
+      "PEAK_OPTION_DEFAULTS" in _val_src
+      and not re.search(r'"peak_soc_floor"\s*,\s*[0-9]', _val_src)
+      and not re.search(r'"peak_soc_floor"\s*,\s*[0-9]', _mainsrc))
+check("...and 20 % is not a number typed into config.yaml on a hunch: it is 10 "
+      "points of margin over the pack's own cut-out, which on the 13.8 kWh "
+      "reference pack is 1.57x the guard's worst measured day",
+      PEAK_OPTION_DEFAULTS["peak_soc_floor"]
+      - PEAK_OPTION_DEFAULTS["bms_soc_floor"] == 10
+      and 0.10 * 13800.0 / WH_BAD > 1.5)
+check("...and it is a SEPARATE KEY from maintenance_soc_floor, whose SHIPPED "
+      f"VALUE ({MAINT_FLOOR:.0f} %) is not this one ({SOC_FLOOR:.0f} %) - which "
+      "is the argument for not sharing them, measured off config.yaml rather "
+      "than asserted: they are a drain TARGET and a spend LIMIT, and the site "
+      "that wants one does not thereby want the other",
+      MAINT_FLOOR != SOC_FLOOR
+      and "maintenance_soc_floor" not in PEAK_OPTION_DEFAULTS)
+
+
+# ==============================================================================
+print()
+print("10. mutation: what defeats these guards, and which check bites")
 
 # Each entry re-implements ONE defeat and reports whether a check above would
 # have gone red. The last row is the honest one: it does NOT bite, and saying so
@@ -1199,7 +1819,7 @@ MUT.append(("blindness() returns None - the degenerate 0 W projection is graded"
 # 2. the frozen term dropped from the guard's inputs.
 MUT.append(("frozen=False - SAFETY-18's term dropped",
             not decide(p_frozen, batt_w=-RAILED, cap_w=CAP_W, reading=None,
-                       achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                       achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S, soc=SOC_OK, soc_floor=SOC_FLOOR,
                        frozen=False).engaged and d_frozen.engaged,
             "part 4: 'THE BACKSTOP: SAFETY-18's runaway ... cut to 0 W'"))
 
@@ -1247,12 +1867,68 @@ MUT.append(("NOT_OBSERVED silently replaced by a peak of 0.0 W",
             "NOTHING - and by construction: the ceiling is max(cap, peak), so a "
             "zero peak is the TIGHTEST possible input to it"))
 
+# ---- SAFETY-24's own defeats ------------------------------------------------
+# 8. the SoC gate removed altogether - i.e. the guard exactly as SAFETY-07
+#    shipped it. Re-derived on the same modelled pack, not described.
+MUT.append(("the SoC gate removed - SAFETY-07's unbounded forced discharge",
+            BEFORE["min_soc"] <= BMS_FLOOR and AFTER["min_soc"] > BMS_FLOOR,
+            "part 9: 'the forced discharge STOPS AT THE CONFIGURED FLOOR'"))
+
+# 9. an unreadable SoC read as a full battery. THE DISARMING DIRECTION, and the
+#    one this project has actually shipped once (NOTES.md 4.4b).
+MUT.append(("`soc or 100` - an unreadable SoC read as a full battery",
+            discharge_permitted(float(None or 100), SOC_FLOOR) is None
+            and d_unread.floor_limited,
+            "part 8: 'an unreadable SoC is refused, and refused with its OWN "
+            "reason'"))
+
+# 10. the gate moved ABOVE the `wanted > 0` test, i.e. graded where it is
+#     degenerate. Counted on the healthy day rather than argued: every quiet
+#     cycle would report the peak was about to be exceeded.
+_early = sum(1 for _t in (500.0, 1000.0, 2000.0)
+             if discharge_permitted(SOC_FLOOR - 1.0, SOC_FLOOR) is not None
+             and not decide(PeakTracker.project(
+                 averager_at(_t, 450.0), B + timedelta(seconds=450)),
+                 batt_w=BATT_NOW, cap_w=CAP_W, reading=None,
+                 achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                 soc=SOC_FLOOR - 1.0, soc_floor=SOC_FLOOR).engaged)
+MUT.append((f"the SoC gate moved above the `wanted > 0` test ({_early} quiet "
+            f"quarters would have alarmed)",
+            _early > 0 and not d_quiet.floor_limited,
+            "part 8: 'an empty pack on a quarter that does not need shaving is "
+            "IDLE, not floor-limited'"))
+
+# 11. rule 8 written `<` instead of `<=`, so a floor EQUAL to the BMS cut-out
+#     is accepted and buys zero margin.
+MUT.append(("validate rule 8 written `<` instead of `<=`",
+            len(rule8(validate_startup_config(
+                opts24(peak_soc_floor=BMS_FLOOR)))) == 1,
+            "part 9: 'so is a floor EXACTLY AT it, which is the interesting "
+            "case'"))
+
+# 12. the floor-limited branch filing `wanted` anyway - a report with no action,
+#     which is the shape a "just log it" review comment produces.
+MUT.append(("floor-limited reported but the floor still filed at `wanted`",
+            near(d_lim.floor_w, 0.0) and d_lim.wanted_w > 0.0,
+            "part 8: 'at the floor it STOPS, and the floor it files is 0 W'"))
+
+# 13. THE SECOND ONE THAT DOES NOT BITE, and it is a real limitation rather than
+#     a defect. Stated, because the alternative is a reader believing this card
+#     bounds more than it does.
+_loop_unbounded = near(r_disch.target_w, 1800.0, 1e-9)
+MUT.append(("the grid-following loop discharging past this floor",
+            not _loop_unbounded,
+            "NOTHING, ON PURPOSE - this card bounds THE PEAK GUARD's forced "
+            "discharge, the thing SAFETY-07 introduced. SAFETY-18's finding "
+            "that the loop itself has no SoC guard is still open, and a `lo` "
+            "limit is structurally incapable of closing it"))
+
 for label, caught, where in MUT:
     print(f"    {'caught' if caught else 'NOT CAUGHT':>10}  {label}")
     print(f"                {where}")
-check("the six mutations that CAN disarm this guard are each caught by a check "
+check("the eleven mutations that CAN disarm these guards are each caught by a "
-      "above - a guard whose checks survive its own defeat is not a guard",
+      "check above - a guard whose checks survive its own defeat is not a "
-      all(m[1] for m in MUT[:6]))
+      "guard", all(m[1] for m in MUT[:6]) and all(m[1] for m in MUT[7:12]))
 check("...and the seventh is honestly reported as not caught, because it cannot "
       "disarm anything: `max(cap, peak)` makes a zero peak the strictest "
       "ceiling there is, so the disarming direction is closed by the shape of "
@@ -1261,6 +1937,11 @@ check("...and the seventh is honestly reported as not caught, because it cannot
       "same zero into FULL freedom, which part 3 shows is why headroom_w() is "
       "not consumed here", not MUT[6][1]
       and quarter_ceiling_w(CAP_W, _zero_peak)[0] == CAP_W)
+check("...and so is the last one, which is not a defeat at all but the EDGE OF "
+      "THIS CARD: the grid-following loop can still take the pack past this "
+      "floor, because the floor bounds the peak guard's own forced discharge "
+      "and a `lo` limit cannot cap a discharge. Saying so here is worth more "
+      "than a green line that would be untrue", not MUT[12][1])
 
 
 # ==============================================================================